I am planning to go to Athens and Santorini this mid-October with my fiance. We are flying from Washington, DC. I was wondering if there is any good mileage program or airlines that I should use for this trip.

I am new to the miles program. Currently I have 40k in UR, 40k in United, and waiting for 50k to appear in my AA account.

I would love to fly business or first class but with the miles I have, it might be difficult so I plan to stick with economic.

I did some research and am currently inclining to AA. What do you think? Any advice is greatly appreciated.