Jackson Hole, Teton and Yellostone.

If Yellowstone seems too big to you (can be busy in the summer), I'd also recommend South Dakota's Black Hills.
Custer State Park is excellent for bison & prairie dogs, in addition to eagles,coyotes,etc. You can easily drive the route yourself, or take a jeep tour. The caves tours are also very interesting, as is the prehistoric Mammoth site at Hot Springs. The nearby SD Badlands also have abundant wildlife, as well as the rugged scenery. You could also view Mt Rushmore & Crazy Horse monuments, drive to Deadwood or Devils Tower,etc. There are numerous hotels,B&Bs,etc for lodging, which may be easier to reserve. There may not be as many elk, but it would still be a thoroughly enjoyable vacation - just different in scenery; more prairie and hills than mountain terrain.

Thanks HotWheels. For the Black Hills area, which is the best/closest airport to fly into? I'd be flying in from Philadelphia, PA.

I'm mostly interested in Custer State Park, at this point. Greg

The combination of the Grand Teton and Yellowstone will provide you with just about unlimited access to bison, moose, etc., etc., etc. Hell, we can even cite guaranteed sights for viewing them!

I saw so many bison that I couldn't count them this past summer in Yellowstone.Grand teton. I LOVED Yellowstone and saw all that I did with a airboot cast on my broken foot; no problems at all. I even was able to walk around the thermal pools which I would absolutely recommend. Yellowstone was one of my favorite trips ever. We flew into jackson Hole and took a terrific bus trip tour to the park. Even though you may have some limitation, I really would not let that stop you. I even learned that bison, as they get older, frequently fall into little holes and break their ankles/foot:) 'that's what happened to me so I could relate. Go to Yellowstone!