I have a United reservation that is DEN-SFO-RNO/RNO-DEN, I also have one that is RNO-SFO-----SFO-RNO. This morning I booked SFO-DEN, which is ultimately to replace SFO-RNO on the second reservation, and RNO-DEN on the first. I don't care about getting a refund for the flights I won't be taking, but I don't know what the best course of action is. Will I be able to cancel the flights without change fees (one intl, one dom, so $400)? I'm guessing the answer is no for that one. The other option I see is to skip those two flights (really I'm wondering if there are any consequences for this) and just do the SFO-DEN leg. If you have another suggestion, I'd be happy to hear it.
Sorry to post this here, but I have no idea where else to post it.

Your post is a bit confusing.

How many tickets have you booked under one PNR? Did you book the DEN-SFO-RNO/RNO-DEN as a roundtrip ticket under one PNR?

When you don't show up for a leg of a flight, all legs after will be cancelled. Son if you don't get on the SFO-RNO leg, the rest of your ticket will be cancelled. This includes all flights under that PNR.

Welcome to Flyertalk.

Easily the most popular question on Flyertalk.

Like MoreMilesPlease said., the answer is if you skip a segment, everything else on that ticket will be canceled. If you want to skip the first segment you need to change the ticket with the airline and pay the change fee and any fare difference.

You have totally confused me on the different tickets and legs.
If the flights you want to cancel are the last ones on the ticket, no problem. Do not cancel that last flight, just don't show up for the flight. No consequences.
If the flights are in the middle of the ticket, all subsequent flights will be cancelled.

I figured that was a bit confusing, it didn't help that I was on my iPhone.

Reservation 1: DEN-SFO-RNO(11/19)/RNO-DEN(11/25)
Reservation 2: RNO-SFO-SEA-NRT-way more-NRT-[SFO-RNO (11/24)]
Reservation 3: SFO-DEN(11/24)

On reservation 1 I would fly the first two legs, the RNO-DEN leg is on the 25th, I wouldn't need to fly that.

On reservation 2 I would fly everything but the last leg, which is SFO-RNO, on the 24th.

Reservation 3 would be a replacement for last leg of each reservation, so from what it sounds like I would be fine to skip those because they are both the last flight on the reservation.

As long as you don't check bags, you will be OK.

Coming back from SIN via ORD after clearing Immigration & Customs I had to pick up my bag and take it to another conveyor for transfer to my domestic flight. The only time I have been through C&I at SFO was on an MR where I just had a carryon, so I didn't have to worry about that. If the process is the same, can I just not put it on the conveyor for the domestic cxn (which was a 14hr layover at SFO before RNO)?
Anyway, thanks for dealing with my fail of a post.

The process is always the same entering the US--you pick up your bags, clear customs and then give the bags back to the airlines for your domestic flights.
So coming through immigration with a layover you can just rip off the bag tag [I think you are supposed to do it after customs (agricultural inspection) so they can see where you've been] and instead of putting it back on the belt to Reno, keep it and check it in for your SFO-DEN flight. If you don't make a habit of doing this, you will be fine for a single flight (or even two).
You might want to ask how much it would cost to change, but my guess is that you would have to cancel all three itineraries and rebook them as two and that the fees would be greater. Unless they are fully flexible (Y/B) tickets.

Don't be surprised if UA calls you and asks that you cancel one of your overlapping segments:
http://www.flyertalk.com/forum/unite...ervations.html

Because chronologically, it looks like you have:
11/19: DEN-SFO-RNO (res1)
11/19-11/24: RNO-SFO-SEA-NRT-way more-NRT-SFO (res2)
11/24: SFO-RNO (res2; you want to skip/cancel)
11/24: SFO-DEN (res3; you want to take)
11/25: RNO-DEN (res1; you want to skip/cancel)