I was surprised to find that the Grand Tetons National Park was not included in IgoUgo's drop-down list. The park is located a few miles from the town of Jackson, Wyoming. It is easily accessible, with several visitor centers, lodges and campsites.
The park's biggest attraction are the Teton Mountain range, for which it is named. Raising up to over 4,000 meters, the Tetons are 'new' mountains. Unfortunately, on our first day at the park, it was raining from a thick cloud cover, and though we knew the mountains should be near, the clouds were so low, we did not get to catch a glimpse, even!
Grand Tetons National Park also offers several hiking trails as well as back country hiking but due to the weather we mainly drove around. The upside of the bad weather was that a lot of wildlife came out. Without ever leaving our car, we saw bison, a few moose, antilope, elk and mule deer.
Fortunately, on our second day, the sun did come out a little, and... the mountains are really there!