We spent a week at Yellowstone NP last year and really enjoyed it. At the end of the tour, you would be tired of seeing geysers. Planning the trip is everything. First visit Grand Teton, and spend a night at one of the cabins in the park, the cabins are really impressive, they are reasonably priced and huge! Three beds in the room and they also got internet access at the office. Then a night at Grant Vilage, see West Thumb and the night show. Spend the 3rd night at Old Faithful Inn (not lodge!), the Inn itself is a historical site, you must walk the entire geyser hill in the late afternoon (see the sunset) and early morning (sunrise), an extra night there is also recommended. Drive toward mammoth, and on the way see many geysers (Madison, Norris), Mammoth is a great place, stay at the official hotel, you will see elks running all over the place in the morning. The next day, go on the horse ride and picnic (you will love it!), and drive to canyon and stay the night there (both the hotel and the cabins are great and cheap), you should also rent a boat at the Bridge bay to roaming in the lake. Spend another night at old faithful inn is also recommended, and then drive threough West entrance and go back