Tons to look at and ride. I've been over there several times on different bikes. I would go ride the west BB park for sure.
(East Side) I would suggest you go out to see Santa Elena Canyon. You can ride a nicely groomed dirt road out to it, or take the SE loop road over to the location. If you take the dirt road this is what it looks like as your getting closer.
There are also some history on the way if you take the dirt road with an old house and the story that is next to the house. I think they raised like 6-8 kids in that house.
Also, Would ride out to Chisos Basin, The road to the top is pretty fun, and the look out at the top is nice as well. If your into hiking, there are some great trails that start at the top next to the motel. Tons to look at even on a short hike. On the North side of the park I would suggest takeing the dirt road up Grapevine Hills Road... There are some really cool rock structures on the right hand side.
(West side of the park) This would be west of Terlingua or Lajitas. If you want a nice Hotel look at the only resort on Lajitas. Its now rooty-tooty. Make sure you ride the road from Lajitas out to Presidio. That's an excellent road. Again, if your into history, there is a very cool 'structure' on the left (heading west) that has been many things to many people. Its a large structure and you can walk and read about it for a few hours. Make sure to get fuel in Lajitas or Presidio. There are a fair amount of border patrol 24/7 on the roads so do go nuts out there. If your interested in heading down some nice dirt roads there are several dirt roads that head north from RM 170. You can do several hundred miles like we did out there. Watch your FUEL, and don't be out in the desert after dark. Boarder patrol told us about that every time we ran into them.
Most but not all the dirt roads on the East side are sandy and some are a total SOB. Most of the dirt roads on the West side are firm and pretty groomed.. Last time I was out in the West side, even 100+ miles out the roads had been groomed and graded for the most part. Kinda crazy but really fun. The only thing stopping you from riding hundreds and hundreds of miles off road all at once is daylight and fuel.
If you have never been to BB I also would suggest you spend one day riding all the roads in side the 'East' park. You will like that. In a nut shell, there you go.... Its awesome ! ::008::
Weather- nice durring the day, cold at night, maybe even 20-30's if your camping... How long? Just depends on what you might like to do.. I would suggest 3+ days.