When traveling with two big dogs, our priority for RV parks is that they offer good areas to walk and exercise the dogs. Some of the better "dog friendly" parks we recommend include:
Green River, UT - Shady Acres RV Park. We chose this park primarily because their ad in Woodall's stated they have a New Dog Park. That caught our eye immediately, and we headed right in. The owners are "dog people," and have a Golden Retriever themselves. The dog area is excellent: large and completely fenced into two separate areas, a large one for big dogs, and a smaller area for little dogs. They even provide some agility equipment and jumps for the dogs! The RV facilities were great, too, the park is clean, and has a strong WiFi signal.
Gypsum, CO - River Dance Resort. For the dogs (and us), the big plus is it's right on the Eagle River! Both dogs swam for sticks until Dawn was tired of throwing them--what's fascinating is that our German Shepherd "Boomer" is a better swimmer and a better retriever than our Golden Retriever "Pardner." Seriously. Boomer was raised by our previous Golden, "Buddy" and we are convinced he thinks of himself as a Golden (perhaps of the "European variety...")
Greeley, CO - the Greeley RV Park. The park itself is old, but the facilities were clean and everything worked. It features a large fenced dog area, 200 feet x 50 feet, with green grass! The dogs loved it, and we could throw the ball for them until they were sufficiently tired (which, unfortunately, lasts only a few hours...)
Salt Lake City, UT - KOA - this beautiful, exceptionally-well-maintained, and centrally-located RV park also offers one of the best dog walk areas we've found. As you leave the back of the park they even provide poop bags. There's a long dirt path along a creek, several large grassy areas for the dogs to romp, and huge fenced area where the dogs can be off-leash.