Star Alliance is definitely the best alliance for Asia, with Singapore, Thai, Asiana, ANA and EVA joining June 18th. And of course United, Lufthansa, Turkish Airlines, etc. Of your options, I would choose Thai- the J lounge in Bangkok is nice, and offers free massages!

Given the two round trips to Europe, you might think about joining one of the more obscure programs, like either Aegean, to get *A Gold status for 20,000 miles. Or you might be able to get there on your Miles and More program- all depends on how much you've traveled this calendar year.

I would think for business travel, you would hub in Singapore and use SQ a lot. But SQ has a poor frequent flier program, with expiring miles, fuel surcharges and exactly the same benefits as you would get with *A Gold anyway. I'm Singapore based, but use UA Mileage Plus, because I also go to the USA quite a lot.