In terms of bonus miles, the 500 OLYMP AA miles is a better deal than the UA Hilton bonus points (due to poor conversion rate from points to miles), plus you'll get AVON1 bonus as well for your 1st trip on AA.

Fokker is something similar to MD-80, but a little bit smaller plane (97 seats only). You could go to AA website, scroll down to "Programs and Services", then "AA and AE fleet" and pick Fokker-100 to see the photo and seating chart.

For UA A319/A320, goto UA website, choose "In the Air" and then "Seat Maps", then pick A319 or A320.