Have you thought about doing a transatlantic trip from SAN to CDG/BRU/AMS? I did SFO-EWR-CDG-EWR-IAH-AUS-IAH-SFO earlier this year on CO for about $450 and netted more than 12000 miles (if I recall). It's a long trip, you'll be jetlagged for a few days and probably won't enjoy Europe very much, but it got me to Silver by February...