I've shot at both places. I went as a guest to ETTS and bought a day pass at Triple C. ETTS was a nice place. They had lots of shooting bays for different types of shooting. They seemed to have a very active match and training schedule, 3 gun, carbine, etc. The 1200 yard range was setup well, but the shooting area was rather small. I would think that only 5-7 shooters could use the 1200 yard range at one time. The staff was friendly and I would go back if we could go durning the week or get there early on the weekend. Also watch the weather, the parking area and shooting area at the 1200 yard range was dirt. If it was wet I'm sure it would be very muddy.
I shot on the 2000 yard range at Triple C. The whole place was very nice. They had lots of rifle, pistol and shotgun shooting areas. I think just about anything you might want to do with a gun you could do at Triple C (full auto, 50 cal, etc). It looks to me that the long range area could accommodate 25-30 long range shooters at one time (probably many more). You can't go down range at Triple C to check targets, so be sure to bring a good spotting scope or rent one from them when you check in. I will definitely go back.