Two suggestions for now:

1) In addition to being able to choose AA/AAEagle only or all carriers, there needs to be a third option, oneworld carriers. There's nothing more annoying than trying to create a trip (multi-city or otherwise) and can't do it secondary to limitations of aa.com

2) Pet-peeve of mine, when selecting the month and day on reservations (or other) please do the programming so that the return date automatically advances to at least the month -- makes one less click for us when booking.