I would say it's probably the easiest commute you could possibly ask for. As you said there are close to 60 flights per day between UAL, DAL, AA, VX, SWA. A flight leaves practically every 15 minutes. I've never ever had an issue on this commute. Well, actually, the only thing that could be problematic is if you have to commute back to SFO on the last flight of the night (it's a UAL flight at 10:30pm). Prepare to be in competition with a lot of AA mainline guys (the ones who are now based there after SFO closed).