This post started as a response in another thread where someone was asking some basic questions about mileage runs. I had attempted a short answer, but just kept typing.

It does not include all of the tricks, but should give you what you need to know to find and book your own MR. It is for the most part exactly what I do in setting up my own. BTW, I learned probably 90% of this on FT, so I am not "giving back" so much as "repackaging".

I will try to keep this up to date as various tools appear and disappear as well as adding additional information on things that I hadn't thought of. But no promises as I have been known to become distracted by shiny objects (like airplanes, or my job).

How to set up and book a mileage run:

Step 1: Determine your starting point: This should be simple - ask someone where you are. In all seriousness, it is a little more complicated than that.

In my case, I live about 10 miles from SFO. I am however pretty easily convinced to fly out of SJC, or OAK if it will save some cash or give me a lot of miles. On one occasion I flew out of SMF (Sacramento) to do a particularly useful MR (went to lunch in Memphis). Other times you might be in a different city on a business trip and might be able to save your company some money by staying over a Saturday night (of course Saturday night will either have you in a completely different city, or on a plane).

Step 2: Determine your destination: This generally falls into three categories: 1) Places you want to go (e.g. visit your brother in BOS). 2) Places you wouldn't mind going (perhaps you've wanted to see the Christmas tree at Rockefeller Center), or 3) Places you will tolerate until the next flight out.

Step 3: Watch for fares. Two places to do this are this forum and the Travelocity Dreammaps Page. Is there a cheap fare near where you are or where you will be in the near future? Does it go a long way to someplace that there isn't a warrant for your arrest? Are these two places a good distance apart? Even better, do you recall someone mentioning on FT that really long routings are possible?

Alternatively, you can skip this step if you were planning some travel that isn't quite as flexible and you would be flying between these cities anyway (in this case it technically isn't a MR, but you may be able to heap on the miles by choosing a creative routing in the next few steps.

Step 4: Confirm the fare exists, and get details. Use Travelocity to find this fare (either by following through the link from Dream Maps or by going to the main page and selecting flexible schedule) and see if you can find some itinerary on it (even if it isn't one that will work for you). Now go to Expedia and try to get this itinerary for the same low price. Before purchasing you will be able to review the fare rules which will include the routing rules.

Step 5: Review the rules: Check for restrictions on days, times, flights, minimum stay etc. See what routings are allowed. See what fare bucket (basis code) that this fare uses.

Step 6: Solve the puzzle. You need to find a string of flights to your destination and back meeting all the requirements of the fare (including routing). Bear in mind that the allowable routings will include possible segments that don't really exist on the airline. Further you can not revisit an airport along the route. Different airlines have different rules, but I believe that most allow a maximum of four hours for a layover on a domestic itinerary (with an exception for missing the last flight to your next stop for the day in which case you can book the first flight out in the morning . . .I doubt I will ever take advantage of this exception). Additionally, all of the flights will need inventory in the appropriate fare bucket. This can be determined (sometimes) on the airline's website. Other tools such as ExpertFlyer (a pay service). can also be used. Finally, you will need to find an itinerary that works for your schedule.

Something else to consider is if your fare requires an overnight (often Saturday night), and you are trying to do this as cheaply as possible, you can often book a red-eye on the eastbound direction and satisfy this rule without needing to get a hotel (there are some occasional westbound flights that arrive a bit after midnight that will work as well). In my own case, I tend to do a lot of weekend red-eye MR's that require no vacation time from work, and get me back in around 24 hours.

Some additional useful tools for me at this point are my preferred airline's flight schedule (to find out exactly what segments actually exist and what time they happen) and Flying Fish (to calculate mileage). When considering miles, keep in mind whatever rules your airline has for accruing mileage. Some offer 50% or none for lower fares or codeshares on somebody else's metal. Also, most consider all segments to be a minimum of 500 miles no matter how short they are . . .so if you can go LAX-SNA-ORD instead of LAX-ORD you will get about 500 extra miles for an extra 30 minutes of flying.

Once you have a good idea of what you are looking for, you can make things a bit more efficient by using ITA to find a particular itinerary. ITA is great as it lets you limit by airline, fare code, as well as intermediate transit points to help you prune your search to what you are really looking for. Unfortunately you can not book on ITA. See some notes on ITA below in post #2 of this thread.

Step 7: Book the dang ticket. Good luck getting your 10 segment round trip booked. You might be able to get some websites to do it for you if you choose the multisegment option and leave out hub cities so that you don't have more segments than fields on the screen to put them (e.g instead of OAK-LAX-SNA-ORD-MHT-LGA-IAD-OAK, enter OAK-SNA-MHT-LGA-OAK). One problem you might still run into here, is that some websites (UA.com for example) refuse to allow you to book tight but legal connections (e.g. 44 minutes in IAD in a recent attempt by me).

So most likely it is time to deal with a person. You can go to your local travel agent where most likely they will think you are insane. Or you could call the reservation agent at the airline where you will hear things like "That isn't a valid routing." or "That isn't a valid connection time." If you know you are right (e.g. you were able to pull it up on ITA - although this is not always a guarantee), hold your ground and invite them to confirm with the rate desk. Most likely they will consider you insane. Or you can go to the airport and go through a similar experience in person (including the part about thinking you insane). In the end you get the last laugh as they doubt their own sanity when they see what it prices out at.

One thing to remember though: don't wait. Fares may be pulled quickly. In the case of outright errors, sometimes within minutes, but even with some intentional fares it may only be around for hours (I have heard/read some suspicions that this is how airlines will communicate with each other without violating anti-trust laws: Airline A offers a low fare in a market that is dominated by airline B. Airline B follows suit with a low fare in Airline A's market in retaliation. They both withdraw their fares in a couple of hours as they realize that this is costing them more money than it is worth. No one wins except the quick mileage runner who got the ticket booked in time).

Even if the fares aren't pulled, the inventory tends to dry up along the better routings as your fellow FT'ers are booking their own overnights in Manchester, NH. On the other hand if the fare stays around for a while you may want to revisit ITA as some inventory may have been released by the airline.

One last note: There is a huge amount of debate on whether a particular MR is worth it. Ultimately, this comes down to the individual. I am willing to spend a bit more to visit a city that I am interested in for a weekend then I am for a strict 27 hour tour of airports. Add to that how many redeemable miles vs. EQM's vs. upgrade currency vs. what you will use the miles/status for later on and it becomes almost entirely subjective.

However there is one common mistake I see people make: Looking for the best deal for the EQM's without considering what they will need by the end of the year. I recall a thread where someone needed (and I don't recall the exact numbers so I am making them up) 8K to make whatever tier they were shooting for by the end of the year. They were debating between two itineraries: one for $250 that would get them 9K, and a longer one that would get them 12K for $300. The longer itinerary had a better yield of EQM's . . .but the extra 3K were basically useless to them as the shorter one would earn the status they wanted - same as the longer one, but $50 and a few hours cheaper.

Sometimes this mistake is not as clear cut - especially at the beginning of the year. Think about what is realistic to acheive in the year. If you realize that the 100K tier is simply something that you will never earn in a year, but the 50K tier is, it doesn't make sense to try to earn a huge number of miles in the first part of the year only to have later necessary travel (i.e. travel you were going to do anyway) bring you to 75K by December. In such a case you will be able to look back and find 20K or so of MR's done during the year were essentially wastes of time and money.

On the other hand, sometimes a promotion, the ability to earn upgrade certs in a particular quarter, or even a really good MR opportunity (OAK-MHT on UA in early '05 comes to mind) will make it worthwhile to do some heavy travelling in the early part of the year).