I visited the park this past December and after 3 days of exploring the backcountry of Big Bend National and Big Bend Ranch State, this was my wonderful re-introduction to civilization!
It was only one day, but really enjoyed my stay here. There is a nice Interpretive center and the volunteers are knowledgable and friendly. I thoroughly enjoyed my extended conversation with a gentleman working at the center as we traded stories of the trails we'd traveled and the wildlife we'd encountered in the Bend.
The Black Bear Restaraunt (Indian Lodge) is decent.. on par with a Denny's sort of thing. The hearty chicken fried steak meal warmed my body and my spirit on a cold night, followed up with gravy and biscuits the next morning. (sure beats canned chili over a camp stove!)
The park is rich with bird watching, javelina, and mule deer. An evening stroll looking for wildlife does not go unrewarded here!
On your day trips, you might consider trying 2 drives:
Hwy 118 between I10 and hwy 17 for a beautiful meandering scenic drive, and Hwy 170 between Big Bend National Park and hwy 67, going through Big Bend Ranch State Park as it follows along the Rio Grande boasts some incredible scenery. (Barton Warnock Environmental center and Fort Leaton SHS are along this stretch and also the "DOM" scene in the Kevin Costner movie "Fandango" was filmed along the roadside)
Also, there wasn't any firewood available to purchase at the park. Either bring your own, or you can purchase it at the store directly across the entrance of Fort Davis NHS.
Oh yeah.. and you can visit the McDonald Observatory just a few miles up the road on some nights for viewing events. There is an information flyer at the park headquarters.
Have fun out there
