The Jitney would work if there are lockers for the OP to store her purchases. Also, if stravels takes the jitney, be prepared to walk from Tanger 1 to Tanger 2 (I think they're called that). Not a far walk but you must cross a major road. I don't remember if there are traffic lights.

The Jitney costs $40 roundtrip. Even for 2, it sounds like the economical way to get there and it will be a nice ride (one you won't have to drive as it's a LONG, LONG drive from Manhattan). I think you might want to look into it.

http://reservations.hamptonjitney.co.../NFDefault.asp

For Riverhead, it's on the Jitney's "North Fork" line. The outlets are the second stop. Not bad.