Some random thoughts:
- definitely worth it to try to achieve mid-level elite in one program. Checking in in non-elite lines in Asia is time-consuming. Extra luggage allowance will come in handy when not flying to the US
- NW and UA are your best bets. One of their main advantage is the low price of intra-Asian awards, pretty much the lowest around. The 30K C award is a great value.
- another is that they grant full mileage for GIT tickets, which are the cheapest ones out of Japan.
- any elite status on UA will get you an E+ seat on aircraft which have them.
- Silver elite on NW gets you a 50% bonus, vs. 25% on UA. 100% bonus for Golds on both.
- UA has many Asian partners with good coverage out of NRT: NH, SQ, TG, OZ. NW currently has MH, should have KE next year, CO Micronesia, Garuda. Advantage UA, except for the fact MH has the best Y product of the above carriers, with two relatively empty 772 daily between NRT and KUL.
- for personal trips to SE Asia, you'll find Tokyo discounters have the best prices and most offers on NW, UA, TG, and SQ, usually.


I'm sure others can provide more comprehensive comparisons between Mileage Plus and Worldperks.