Just please don't fly all the way there to spend two weeks in Phuket. Lame all inclusive resorts are a hell of a lot closer to home.

For inter-southeast asia...you can fly AirAsia for about $20-50 each way. Tons of flights in the region and very convenient.

For GUC upgrades, I'd imagine DTW-NRT-BKK is probably your best bet. You can OJ to/from SIN if you want to switch it up...but rumor is those 767's on the route make GUC usage difficult for the SIN-NRT hop. DTW-NRT on the other hand is a 747 with plenty of D1 seats..and the upper deck!