Just to update this thread with one "solution" that we found...

We've found that timeshares can be an excellent way to get considerably more space. It requires quite a bit more planning and flexibility. It also has the advantage that it can be quite a bit cheaper if you play your cards right. It's amazing how similar timesharing is to frequent traveler programs - if you learn the ins and outs of the system, you can really do well. There's a ton to know.

The best resource I've found for timeshares is the TUGBBS.com forum, and that's where I've learned the ropes. Two cardinal rules of timesharing: 1) It's almost never a good idea to buy from a developer. Buying resale is 50-99% cheaper. 2) The maintenance fee is far more important than the upfront price. There's a reason many units are listed for $1 on eBay (and still don't sell).

Here are some of the basics:

1) With each timeshare unit you own, you usually own either a fixed week or a floating week (where you pick a week in a certain season), in a specific size unit (or sometimes a specific unit), at a specific resort, sometimes with a specific view. Some use a points system. Each has advantages.

2) If you want to exchange your week with others, there are two main exchange companies (RCI and II) where you deposit your week and can pick a comparable week that someone else had deposited.

3) If you join an exchange company, you also have access to rent extra units from them. Many are expensive, but some are in the $200-$400 range.

A brief rundown of the costs associated with timeshares:

Upfront costs: Cost of the unit (many in the $1 - $1000 range resale, some brand resorts are $5-10k, and from the developer it's usually $10-$50k), plus closing costs (under $500), plus exchange company signup fees (in the $100 range).

Annual costs: Maintenance fees (anywhere from $250 - $2500 for each week you own, depending largely on the area) and exchange company annual fees (under $100).

Transaction fees: Exchange fees (typically $100 to $200 per week exchanged), rental cost of any Extra Vacations you buy (some in the $250-$400/week range, sometimes on sale for less).

A few things that can make it difficult for many:

1) With some of the best resorts, you have to book a year in advance to get in. Even at that, sometimes you have to own at that resort or in that group. There's often some decent last minute inventory that's sometimes really cheap, so flexibility pays off.

2) Few resorts are in or near big cities, so it's usually not useful for business.

3) Usually, you'll need to book 7 days at a time, Fri-Fri, Sat-Sat or Sun-Sun.

4) You don't get daily housekeeping (or you have to pay extra if you want it).

5) It's a long-term commitment. You can't really do this (easily) for just a year or two.

So far, we've been making out very well with timeshares. Some of the things we've booked (with the prices including associated maintenance and exchange fees):

1) A couple separate weeks in 2BR units in Branson for around $200-$250 per week (Extra Vacations). (We have family near there, and we usually spend more than that for a few days in a hotel).

2) Two weeks in 2BR units in Hawaii for a total cost of less than $100/night (one Extra Vacation, one exchange). (We normally pay more than that for a small hotel room.)

3) A week over Spring Break with three separate 2BR units in Orlando for an extended family trip to Disney. This will cost about $600 per unit (all Exchanges). We could have found cheaper, but this is one of the best non-Disney ones in Orlando, which normally rents for about $1200/week.

4) A week in a 2BR Disney Vacation Club unit for under $600 (Exchange). (That's about what they charge per night for rentals.)

5) A week in a 2BR in Galveston for $225 (Extra Vacation).

6) A week in a 2BR in Vegas for $490 (Extra Vacation).

7) Two weeks in a 2BR in Orlando for about $900 total (one Extra Vacation, one Exchange). We were already booked for two weeks in a Disney package (Value resort [260 sqft], park tickets for 4, free dining) for $2500 and was considering paying another $1000 to upgrade to a Moderate resort [314 sqft]. For less money, we're now in a 2BR resort that's about four times as big.

That's about $6000 in expenses for 12 weeks of timeshares, which is about $500/week or $70/night. This is all in 2BR units with plenty of space and full kitchens. And some of these were more expensive than they needed to be - I'm still learning. We normally spend more like $100 per night for hotels, occasionally getting upgraded to a Junior Suite, but never to a 2BR.

So I guess what I'm saying is that if you travel a lot, have a family larger than 4 people, have enough flexibility, and are willing to learn something else, timeshares can be a really good, economical option. Just make sure to research it thoroughly before you jump in. There can be some real pitfalls.