AS of March 2010, most of DTD was open until 11pm, or midnight on weekends. Ian't say off the top of my head how late the buses run, but it is later than the shops are open.
Guest Relations (407-828-3150) - this is the number for gust relations, they can probably answer you exactly.
Also, you don't say where you are staying, or where you are eating. There are numerous notable expections to the DTD route.
If, for example, you are staying at the Boardwalk, BC, YC, Swan, or Dolphin and want to dine at any of those - then oftenthe fastest way to get around is simply to walk. There is also a boat that connects all of the above to Epcot and HS.
If you are at any monorail resort, the best way to go between other monorail resorts is via monorail.
If you are at any monorail resort and will be finishing up dinner before MK closes, then it's pretty quick and easy to hop on the monorail, and transfer over at MK (typically you'll transfer to a bus).
There is also a boat available among GF/Poly/MK, and a boat that connects The Contmporary to Ft. Wilderness and WL. If you are dining at one of the shows (Luau or Hoop de Doo) then disney will have buses waiting after th show lets out. WE din't take them, but I thikn they run fairly directly based on need. Each bus might make a couple stops - but you don't have to go all the way to DTD.
If you are staying at one of the resorts near DTD, there is a boat that run in that area.
If you are one of the value resorts, then that's one of the slight limitations of the values. There's no table service restaurants AT the values, and transportaion to the other resorts typically menas taking the DTD bus exchange route. (And thus having your own car is a BIG plus.)
If you have a car, then you need a designated driver. Having a GPS is a great idea too. Routes in DIsney are marked, but not quite as well as the highway. Some roads are one way. You can request a free road map from any Disney resort, but a GPS (on your smart phone perhaps?) is very helpful. Making a wrong turn at Disney can be very time consuming!
One last possibility is to change a few of your dinner reservations. If we are staying in the Epcot resort area - we'll do more dining in that area. If we are on the monorail loop (the few times we've done it) mostly we'll pick from among those reosrts. I fyou are staying at a mod or deluxe, then it is very worth trying to dine at your home resort for the convenience alone.