If it were me, I would pick Boston rather than Manhattan. Even though NYC probably has more choices for overseas flights, I prefer the life style in the Boston area over Manhattan. (Actually I prefer the mountains of CO over anywhere and live in Steamboat Springs in the winter but that's not on your list.) If there is a flight you want out of NYC, its a short train ride or commuter jet to get there.

If it were me, I would keep the Useless Air account and just add miles as they come from partners unless its such a small amount you don't mind letting them waste away.

I would also get an AMEX Membership rewards card so you can transfer to several different airlines or one of the Capital One cards which is probably a better deal since you can use the miles on any airline and they have the best policy on foreign currency purchases and ATM use (no fees but who knows how long that will last).

One last thought. If you plan on doing a lot of flying in Europe, the LCC's like RyanAir and EasyJet have much better deals most of the time even if they fly out of some remote airports and have really strict baggage allowances. No status though so if that's an objective, search a long time ahead and majors like BMI have some really cheap fares. Just flew from LHR to VCE for $100 on BMI and got miles on Useless Air.

Enjoy your retirement, I sure am.^