Another piece of advice: if you don't have a reason to need to go to NRT on the outbound and KIX on the return, do SFO->KIX and NRT->SFO. If you're looking at late March/early April, then your return will be after the second SFO-NRT (and v.v.) comes back at the end of March (I believe 3/28), which will help your upgrade chances.