Budget tips for Yellowstone:
- Do not enter the park with anything less than a full tank of gas. It's easy to underestimate the vast distances within the park, and you're very likely to encounter traffic. You can buy gas inside the park, but you will pay for it! Much better to buy before you enter.
- Similarly, come prepared with basic items you may need: Asprin, batteries, etc. They'll be readily available at the gift shops, but -- just like the gas -- you'll pay for them. The lake in Grand Tetons is one of the most beautiful places I've ever seen in my life, but the tiny bugs just about did me in; bring bug spray.
- Take advantage of the ranger-led programs, which are mostly free. We've always found them to be very informative and fun (and we've partaken of many ranger programs in parks across the country). You mentioned kids, be sure to look into the Junior Ranger program for them. Wonderful lessons, mostly dealing with wildlife and ecology. You can look these up online before you leave. Yellowstone also has paid programs available, but we haven't done any of those; thus, I cannot comment on their quality.
- Come prepared for any weather. I've visited Yellowstone twice -- both times in July. The first time we were comfortable in shorts and tees. The second time the weather was in the 40s; we had jeans but nothing other than short-sleeved tees, and we were forced to buy $50 sweatshirts. While the quality was good and we still use them, I could've made better use of that money.
- Safety first: Never leave food in your car. A bear is capable of ripping your car to shreds to get at a loaf of bread. It's better to buy your food inside the park. Every "area" has a restaurant or cafeteria in its main area, and every gift shop has a grill/sandwich bar. The prices are higher than you're used to paying at home, but they're not outrageous considering that they've brought that food /someone to cook it into a remote area. You should be fine, though, with canned sodas and water.
- Don't skip the town of West Yellowstone. We loved the Grizzly and Wolf Center (not quite the whole name, but you'll find it) and the pancake house (Bear is in the name?). Bring your
AAA card for a discount on the Grizzly/Wolf Center. They have a rodeo too, but we'd just gone to the rodeo in Cody, WY. I wanted to do the Imax movie, but we ran out of time. You might consider staying a night in West Yellowstone instead of inside the park. Honestly, there's not a good answer as to where to stay in Yellowstone /just outside Yellowstone -- nothing's particularly convenient or cheap. Most recently we stayed in the Canyon area; it was like a rustically-themed Motel 6 . . . and three times the price. However, it was centrally located, safe and clean, and those things mattered more than economy or luxury.
- Note that your rooms will not have TV. You won't find much to do after dark, so I suggest packing some board games for family entertainment.
- Note that your ticket into Yellowstone is $25 (it was a couple years ago that I went -- you should verify that information), but it gets you into BOTH Yellowstone AND Grand Tetons National Park for the whole week.
- Finally, don't skimp on activities. You're traveling a long distance to a place that you may never visit again. I completely understand needing to stick to a budget, but do the Roosevelt horseback dinner ride, do raft the Snake River in Grand Tetons. The memories will last a lifetime.
. I went by google maps for drive times. Google maps actually takes you on the interstate up through Montana and then back down. Is that a more reliable course? We may end up spending one night in Colorado Springs and then driving part way to Yellowstone the next day. Where would be a good place to stop in between? Cheyenne? --Katie
? The Jackson Hole airport is a neat little airport, gorgeous mountain views as you fly in..... just sayin' 
