Hi folks,
I've been lurking for some time now, and finally decided to become an active participant as I begin the process of building up rewards. I'm starting from pretty much nothing - I have 10k miles in United, and 50k in Southwest, but that's it. I do have existing accounts with most of the US legacy, but they haven't seen activity in 4-5 years.
I'd appreciate some help in developing a strategy for my credit card apps. I don't travel all that much generally, maybe 3-4 trips a year BOS-BWI (thus Southwest). Mainly, I'm looking for rewards that would get me international business class flights. I'm fine with any continent - I just like travel

I don't really care about domestic awards or elite privileges.
What programs should I be working hardest? It seems that AA would be good for the Oneworld redemptions, and United for Star Alliance. Are Amex MR worth it to me? Chase UR seem good. Most important question is, are there any cards that I should apply for right now? I'm hoping that with the CO/UA program merge in January, they'll have a big promo card of some kind, so that might be a good thing to wait on.
I'm grateful for all suggestions!! Thanks for all the great advice everyone's already posted, here and elsewhere.
P.S. If this belongs in a different forum please go ahead and move it...it felt most appropriate here.