After spending a week visiting my sister in D.C., I need to get to NYC in time for a 9:00 a.m. tour. Looks like flying is the best way as compared to the train. My sis lives in Alexandria so I will be leaving from Reagan. But I need help with the following questions:
1) What's the best airport to fly into NYC that has the quickest/easiest access to downtown Manhattan?
2) How do I get from the airport to downtown?
3) When looking at different flights with different arrival times, how early would my flight need to arrive in order to wait for luggage at baggage claim, find transportation to the city, and be in midtown Manhattan no later than 9:00 am?
I really appreciate your help!

You better take a 6 a.m. plane to Laguardia, arriving in NY around 7. It'll take you that long to get your luggage and take a cab to the city for your 9 a.m. tour.

Only flight that's reasonable is USAirways' very first shuttle flight, 6am-6:59am, DCA-LGA. Get luggage, then taxi to hotel.

The next one is DL's 6:50am-7:49am. May be able to make it, but very very close.

And it doesn't solve you luggage problem.

Agree that the 6am flight is the only option - otherwise your chances of making a 9am tour are almost nil.

Your other option is an Amtrak train (Acela or regular) at around 5am from Union Station that would get you into Penn Sta at either 7:50 or 8:15.

(Don;t know which is easier/faster for you to reach - and allow for check-in and security.)