Durhamtown plantation is mainly for dirt bikes and four wheelers. Mike recently added some areas for trucks etc though but I have not gotten a chance to check them out. As far as dirt bikes and quads though, you cannot find a place better IMO.
Gulches is sweet for sure. Lots to do and they really help you get started wheeling. Since you havent gone out there before they will have a ranger show you around. There are maps and signs with difficulty ratings as well as a lot of one ways for safety. Skip has done a great job with it and there is tons of fun for rigs and drivers no matter what capability level.
You can find lots of video on both places on youtube. I just posted some pictures from Gulches here http://www.jeepforum.com/forum/f163/...82/index3.html
If you go to either, let me know. The girl and I may be able to come out.
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Gulches Off*Road Vehicle Park