I was in Big Bend the week of March 25. It's been too dry and there isn't much blooming going on. You'll want to visit the headquarter visitor area first to get the lay of the land. The ranger-led day talks and the evening programs are always interesting. The best campground is Rio Grande Village. There's quite a few back roads to try. For about 4 hours take the river road (not actually on the river, just parallels it) from the Rio Grande Village area to the Castalon area. You will go by an old mercury mine that you can check out. Be sure to visit the hot springs. Water is 105 degrees. Was muddy when I was there but maybe enough waders have cleared it out some now. Its built right on the banks of the Rio Grande, but due to the droughts it was about 5 foot above the river level. The only restaurant in the park is in the Chisos basin. Higher altitude in the pinon pines. The closest facilities outside the park are at Study Butte near the west entrance. Numerous places to eat, a few motels and the nearest mechanic. I've probably gone out there about a dozen times over the last 40 years.
1983 CJ7, 258I6, T4, Dana 300, 2" Lift, 31x10.5x15 DuraTrac