What is the best way to see nature at its best in Yellowstone National Park?

[Lisa]

I am planing a trip to Yellowstone for next summer, but time will be pretty tight as I will only be getting 10 days of vacation time. I would like to view as much of the scenery and wildlife as possible.

Could you please tell me some of the DON"T miss spots in Yellowstone?

Also when would be the best time to visit?