Wow United's new site is good. I'd suggest India because it's possibly the most difficult Eurasia location to get to from the US (and IMO more interesting to visit than most of the world). Or Moscow which was on one of your trips.
I can do SFO-FRA-DEL-BKK-NRT-SFO for 147k + $200 through United. (United's award search is SO much better now). BONUS: get to fly on a 747 (still cool even if old as eff), a 787, and an A380.
Hard part is hotels. Also Frankfurt wouldn't be my first choice but United partners don't have a ton of directs from SFO to Europe.