Thanks for your input everyone! We ended up going with the Graco MySize, which worked very well. We used it both front and rear facing on the plane, armrest could stay down, toddler was comfortable enough to fall asleep, and it met almost my criteria. The Graco Contender is lighter but we liked some of the ease-of-use features on the MySize (easier LATCH connectors for example.) We used it on a Brica Roll and Go, which worked great in the airports. Most importantly, the front facing belt path is closed so the airplane seat belt buckle can't be felt in the car seat. The tray table couldn't be used, but you can't have everything really.