IME, zip code searching is not reliable. Search on address and/or on metro instead. I almost always search on address, the exception being when I'm taking a road trip and want to try and find things along the route -- then I use metro search. (Edited to add: of course in the case of a small town like Easton, slim pickings are likely. The nearest iDines are 30 to 40 miles away: on the beach, in Annapolis, and in another small town to the south. Metro search shows those.)

As for recommending restaurants, you cannot really recommend them specifically to AA's version of Rewards Network (so this thread ought to remain in the iDine forum).
I've managed to get one to re-up and two others to take a serious look at it, though neither joined.

Two steps:
Talk it over with the owner and send them to http://www.reachdiners.com/ and (866) 518–3463
Send an email to [email protected] and recommend the restaurant, providing as much contact and other info as you can (e.g., phone, email, physical address, web site, cuisine, price range and why you love it).

Rewards Network is downright eager for these kinds of referrals because when they contact the restaurant it is not quite a cold call.