I recommend signing up for the Mousesavers newsletter and perusing their website. They often have reader discounts for those hotels.
We stayed in the Doubletree Guest Suites in July 2009 on a Mousesavers rate, and it worked out really well. It's an all-suite hotel, so each room sleeps at least 6 and has a living area and sleeping area.
One thing to consider with off-property hotels is that some charge for parking and other things, so it's good to make sure to account for all costs. It's still likely that all the hotels down there will be cheaper, and probably include some form of breakfast (except the Hilton).
The bus transportation in that area isn't as good as Disney's but it's sufficient. We took the LYNX from the airport to save money (the stop was right across the street from our hotel) and were perfectly find relying on the provided transportation the whole time. I really enjoyed the proximity to DTD, because it made resort hopping easy. It was also a short walk to a grocery store.