For someone who has not been to a National Park, I typically recommend buying one of the Photographer's Guides to the park. For Yellowstone, the one I recommend is by Joseph K. Lange. While I expect you can buy it in Yellowstone, the second edition is now on Kindle.
http://www.amazon.com/Photographers-Guide-Yellowstone-Tetons-Joseph/dp/0811735559 (I have no connection to Mr. Lange.)
Like most books of its type, this book will recommend a certain focal length lens to use at various points and, most helpfully, what time of day produces the most favorable light. E.g., A photo of Lower Yellowstone Falls from Artist's Point at 10:30 am in summertime.
I do suggest you have your 18-105mm lens you have to photograph the
hot springs. I would think that most of the time a 35mm will not be wide enough because the boardwalk is too close to the thermal feature.
There is a flat geyser area not far from the west entrance you may want to check out around sunset. I missed a spectacular shot of the setting sun illuminating the steam at Lower Geyser Basin 10 years ago and I'm still kicking myself for it.
There will be plenty of wildlife in Yellowstone, predominantly Bison and Elk, while you'll have a decent chance of seeing grizzly bears (though a LONG telephoto lens, of course) and moose, you may want to go to the Tetons for a better chance on the Moose.