Yellowstone

We're planning a family trip for next summer to Yellowstone. We're starting to look at some different ideas on what we're going to do. My parents are brother's family are going to join us. My parents will bring their travel trailer and we're looking at our options. Anyone know about good spots for cabins or places we could rent a trailer and either have it spotted or pick it up pretty close to the park? I already did some checking on motorhomes and that's a little pricey for what we want to do. Also, recommendations on what to see or where to go. My parents know the areas pretty well...we went there a couple times when I was a kid. I'd love to do something a little different if there's something like that. I'd also like to find a spot that might be good for some trout fishing with the kids.

Ideas and suggestions?

I grew up in the North West of Montana. Used to hunt down near West Yellowstone. Been To Yellowstone many times both winter and summer, one can not see it all in a life time, Also enjoy Teton national park.
I grew up in the shadow of Glacier National Park in the Flathead valley. Have not been back in over 25 years.
Make the best of your trip and take lots of pictures for the memories.