We went to Yellowstone last summer -- oh, what an incredibly beautiful place! I absolutely want to go back someday.
Random thoughts:
Again, it is absolutely beautiful. Rivers and waterfalls, Ponderosa pine. And the variety! Have your camera ready at every moment.
We stayed in the Canyon cabins and were underwhelmed with the quality and service. Our room wasn't ready for hours after its promised time, and it was very expensive for what it was. It was just a plain hotel room, no different from a Motel 8. I understand paying for location, but I wasn't all that pleased. I would say that next time we'd stay in the small town of West Yellowstone, but the traffic coming into the park every morning is horrendous. I don't know where it's best to stay. The one place I would never choose is the Old Faithful area; the crowds, the crowds! We had trouble just getting a parking place.
We enjoyed the Grizzly and Wolf Center (might have that name slightly wrong) just outside the park door in West Yellowstone. Take your
AAA card for a discount to their fairly expensive tickets. Well worth a trip! It's a tourist town with plenty of restaurants and shops. They have a rodeo, which we did not visit since we'd already come through Cody, WY and had been to the rodeo there.
Do not enter the park without a full tank of gas. Sure, you know the park is large, but don't underestimate it! You can buy gas inside the park, but it'll be expensive.
Drive carefully. Drivers in Yellowstone seem to have no sense whatsoever. Be prepared to come around a bend and see traffic stopped and people getting out of their cars to take pictures of a bear and its cubs or a moose.
Last summer the very popular Uncle Jim's trail was closed. That trail contains metal steps, and they washed away in a flood (at least I think that's what they said). With money being tight, I'd be surprised if this has been replaced.
Each area of the park has a cafeteria and a gift shop with an old-fashioned sit-down lunch counter. The food was plain but good (burgers, tuna melts, chicken sandwiches), and although it wasn't cheap, it also wasn't outrageous.
We hiked up to the top of the mountain near Old Faithful and watched the erruption from that vantage point. It was a steep hike, but a good choice. We were away from the crowds and had a great viewpoint. Old Faithful wasn't a hallmark experience.
Definitely plan time to visit the different areas of the parks. They're so different! I loved the Artist's Paintpots, the Mud Volcano, and the Black Sand Basin area.
Also, visit as many of the park's museums as possible. They're all so different! Some focus on geology, others on Indian art, others on the people who built the parks!
Be careful of buffalo as you go through the park. They're often just sitting near the cars in a parking lot, minding their own business. We did a Buffalo Safari in Custer State Park (wonderful trip! We had a fantastic guide, and we saw and learned so much from him!), and we all have a healthy respect for what a buffalo can do to you.
We did the horseback ride /chuckwagon dinner in the Roosevelt area -- wonderful fun, even though a horse bit me. We're not really experienced riders, so they matched us up with easy horses. It was a relatively expensive meal, but it was good food, and the scenery was incredible. You can either ride, or you can choose to arrive in a covered wagon. Most people rode the wagons.
You cannot predict the weather in Yellowstone. We were there in July, and on the second day a cold snap forced us to buy sweatshirts. We already had jeans and boots. It was 40-50 degrees, plus wind chill! And to think, I'd been concerned about the hotel not having air conditioning!
Our favorite, favorite hike though wasn't in Yellowstone: It was the Hidden Falls hike in next-door Grand Tetons. Wow, what incredible sights. You start at (oh, I could be wrong here) Jenny Lake Lodge, where you take a ferry across the lake (small charge for this 30-minute ride). The hike is steep but not so difficult that an average person can't do it. The falls are 90% to the top, and they're lovely. The view from the top-top is wonderful: There's a huge granite rock to sit upon while you take in the view, and little chipmunks are everywhere. You can see out all over the lake and the mountains. Once you get to the Hidden Falls area, there are no facilities of any type (well, except the dock where the ferry drops you off), so pack in your water, lunch, and be prepared to "go" behind a tree.
In the Grand Tetons we stayed at Signal Mountain Lodge. I'd classify this as expensive but worth it. We had a two-bedroom/one bath cabin. Tucked into the woods, it was absolutely adorable. Also plenty large for the four of us. However, if I had it to do again, I might pop for the even more expensive cabin with the lake view. I know we would've sat out on the porch for hours. In general, Grand Tetons is more expensive (but less crowded) than Yellowstone.
I also recommend the Trapper Grill at Signal Mountain Lodge. Moderately priced, it's good, hearty food. You can eat inside or out on the deck overlooking the lake.
I remember bugs being something of a problem in both Yellowstone and Grand Tetons (much worse in the Tetons), so bring along some Off.
We did the last float trip of the day (Snake River from Signal Mountain Lodge), and that was a great choice. We saw so much wildlife at that time of day: eagles, beaver, moose, elk, and more. Our guide was fantastic, telling us all kinds of things we never would've known on our own.