backpacking trip in early fall. We'd like to go somewhere nice that isn't too many hours away from Salt Lake City.

The biggest requirement is that we need to not go up too high in altitude. We did this last year and went up in the Uintahs, but my one brother who lives at sea level got altitude sickness pretty bad (we had to abort and get him back down). So I'm looking for something that isn't much higher than 5000' or 6000' above sea level.

Any recommendations?