Wow, thank you for all the detailed and informative responses. Very, very helpful.
It seems like things would be a lot easier if there was one central website where everyone (non-rev'ers, JS'ers, etc) could view all available spots on all available airlines, and list for those spots (with the knowledge that weight issues could bump them at anytime.) Basically just like a crew bidding system, but open to everyone. Seems like it would take a lot of the stress out of everyone's commute. Of course, there'd be a cost associated with building and managing that site, and no airline's going to want to cover that cost.
Sounds like SFO-ORD is do-able, SFO-LAX should be pretty easy (given that there are also OAK-LAX and SJC-LAX flights). SFO-DEN and SFO-MSP sound pretty miserable from what I've heard...
And for me, an OAK commute would be perfect since I'm literally 10 minutes from the airport.
Thanks again, folks -- I really appreciate all the help.