Any recos: Yellowstone & Grand Tetons NP?

[GregS]

We are (God willing) heading to Yellowstone and Grand Tetons national parks next month. Any tips on where to go for wildlife sightings?

We do have the guide books and read the general recommendations, such as Hayden Valley, but anything more specific than that or maybe some places that aren't full of other tourists that read the same guide book?

Thanks