Check Kayak.com for the rental car. I am getting a much lower price than you have. Book the cheepest car, check the web site often. The prices change very often. Grab the cheepest price.
Also, always use a hotel that offers free breakfast. Eat well.
Buy a cheap cooler and fill it with snacks. Buy only one meal a day..

When we were in and around Sturgis, first week of August last year it was close to 100 or over every day with a very dry wind. Being from Florida it was a change from the high humidity we have here. When I say, dry, it was dry.
The weather can change fast and can be cold at night. No way of telling.
A couple of years ago we were wearing leather jackets and pants in the mornings to protect against the cold.
Have to take clothes for any weather condition, including rain, which you will most likely encounter!
It is worth it to see the scenery, simply breathtaking!

you can't take a stove on a plane? how about an electric one checked in? We're doing that for our trip too. Didn't think there would be an issue....we can keep it in it's original box. anyway if they buy a coverter, they can use an electric one to cook during camping?

sleeping bags are tough to lug with you since they're bulky and take up alot of room. you can buy really cheap ones at walmart for $10 then donate it to goodwill before you leave.

oh, and in park lodging can be as cheap as $69/night and this will save you the gas from those long drives in and out of yellowstone/grand teton. If you book early, you can still find them.

We're doing this same exact trip for 2 weeks and 3 weekends (and the extra holiday for labor day). Go look for lodging in park now so you can still get them cheaper. I would suggest those "in between" hotel stays be in yosemite. those drives can be very long and eat up alot of gas.

i meant to add "in reverse order". we're flyng in to idaho falls and flying out of rapid city. our full size car is $802. I checked to make sure about drop off fees and no additional drop off fees were listed, it was built in the prize. our flight we paid with our miles which is better for open jaw ones such as this. good luck!

Well, it looks like I can save a ton by flying into Denver and out of Salt Lake City. It is extra driving, but saves me about $500 on the rental car and another $200-300 on airfare (for both of us). I may skip the Idaho visit with my cousins and plan on catching them next year. Thanks to everyone for their advice.

We always take a small stove on our trips out west just to make our own good coffee in the morning. We purchased a small camp stove that you can just screw in a propane canister which we buy once we arrive out west. The propane can also be used on our camp lantern if we are camping. No problems getting the stove through security.