When we lived in eastern Idaho our trips to Yellowstone and Grand Teton in the spring, fall and occasionally even summer proved you can have an enjoyable experience with a little planning and patience. You just have to go into with the right attitude and a willingness to share the experience. Besides, solitude can often be found just a short distance down a trail. I do recommend investing in bear spray and knowing how to use it.
Thanks for the kind comments, Batman! Yellowstone is worth visiting. As you say, homework and attitude.