MSPeconomist speaks the truth, on many counts. Silver probably doesn't do much. Does she fly with you? You can check the bags, free.

I like the idea of using the SWUs for the upgrades, and saving the miles for actual tickets. Note his last sentence. If you want to go with the SWU option, activate this benefit about 4 days before you plan to use them (maybe 3, idea is to get them into the system). That way, you optimize the full year.