We have lots of choices both inside the park and outside in the west Yellowstone area.  Here are some that interested me.
Inside the ParkInside the park the big hotel/lodges have decent dining spaces. I found the following are interesting.


On the Shore of Yellowstone Lake




OLD FAITHFUL INN DINING ROOM




Outside the Park in West Yellowstone AreaHere are some I am still researching:


Hanks Chop ShopThe Buffalo BarMadison Crossing Lounge