We just came back from Yellowstone. We stayed at fishing bridge. Fishing bridge is a RV parking lot. We got a spot back to back with my sister and her RV. My only complaint was the septic hookup stuck up so far out of the ground that I couldn't empty my blackwater tank more than half empty. For a RV parking lot fishing bridge was above average. I don't know how they would do full hookups without the parking lot feeling.
There are lots of things to do in the west side of the park but the west side feels much more commercial. I.e. lots of places to spend money. When we made reservations they told us not to bother bringing our bikes or kayaks. I am glad we brought our bicycles and wish we brought our kayaks. The north side of the park is less traveled and less commercial. We liked the north side of the park the most. Just like every campground supplies at the stores where 2x to 3x what we would have paid at the supermarket at home.
As expected the restraunt we stopped at in the park was expensive and mediocre. The last few days we packed a cooler and a grill in the back of the truck and pulled over to one of the picnic areas when we were hungry for dinner (About 7:00pm). The first night we had the entire picnic area to ourselves (The entire area not just the picnic spot!) The second night there was another friendly family there that we chatted with a bit. The third night a coyote decided to lurk in the outskirts of the picnic area waiting for us to leave. (That was adventurous and fun). Eating at the picnic spots felt much more like capming than eating in our little section of the RV parking lot.
The best advice I have seen on here is to stay in 2 or 3 different areas to minimize driving. There are 2 loops, an upper and lower loop. The loops are 45mph and there are more than the ocassional traffic backup due to people pulling over to photograph a herd of bisen or an elk or moose. So it took us about 2 hrs to get from the west entrance to Fishermans bridge. You can easily spend 4 hours of driving in the car just to navigate the southern loop especially on the weekends. I wish we had stayed in a couple different areas of the park.
The park is busiest during the day. It was much nicer and more peaceful during the evening... except the mosquitos! Both my brother in law and I enjoy photography. My brother in law enjoys photographing the animals and I enjoy photographing scenery, particularly scenerey in the background with family in the foreground. Together we had lots of fun but I will admit I was buffaloed out by the time we stopped on the side of the road the the hundredth buffalo. :-) I must have taken pictures with 20 different cameras. Pretty much everywhere we stopped I would take group shots for others with their cameras. Most all of them recripricated.