On the off chance F is not available, MCS will almost certainly be available. You only get one bag with MCS instead of two but if you only have one it may be worth it if you are really only looking for a few free drinks. My experience is primarily SFO-LAS, and I usually end up getting at least two rounds of drinks in MCS.

Also, I don't see this upthread but the upgrade procedure at VX favors those who check-in right at the 24 hour mark. To upgrade, just select any available F or MCS seat during the check-in process. The system will then ask you to pay the upgrade fee. It's a really easy to use system.