Yes, the Pelican area, then over the pass to the Lamar. One issue with this route is that you have to hike 11-12 miles fairly efficiently to get over Mist Creek Pass to the first campsites (3T3 and 3T2), since you are only allowed to be in the Pelican valley between 9 AM-7 PM (it's griz-infested). Then there's the logistical nightmare of coming out at Soda Butte Creek and having to somehow get back to Fishing Bridge. It would be best to have two vehicles (like you would need to do if you hiked the Bechler River).
Slough Creek is reputed to have lots of wildlife, but when I spent 3 nights there last July I only saw one bison, two deer, and a pair of pine martens. Several years ago I hiked Pebble Creek, and at the head of the valley one night I was treated to a prolonged wolf pack howl-fest, but I couldn't see them in the dark. A pack of coyotes down the valley joined in as well, so I was surrounded by noise. They all like a good howl, and they'll sing at every opportunity.
The one critter I hate to share a campsite with is a bison. They do what they want, they're actually strong, fast and agile, and they're a heck of a lot bigger than I am. The same goes for moose, which I hate maybe just a little bit more because they act so goofy. I haven't seen a moose yet in the YNP backcountry, although they exist.
Generally, wherever you hike/camp in Yellowstone's backcountry, you'll see some sort of wildlife. It's loaded with critters of all shapes and sizes.