Seven on Prospect in Peoria Heights is excellent. You almost forget you're in Peoria when you're there.
Jim's also is superb. I've also heard good things about Red Zin. Farther away from downtown, the Fish House and the Lariat Club are good choices.
And one of the best things about Hoops? They serve food until 4:30 a.m., seven nights a week. Richard's downtown also serves until about then.
For a medium-sized city in corn country, Peoria has some surprisingly decent dining.