Scruffy gives good advice. I was born near Peoria and now live in Providence. I fly into Chicago (usually O'Hare, but Midway is good also), then drive. I've found I can't depend on the puddle-jumper flights to Peoria, generally always delayed, often cancelled.

It's an easy drive to Peoria from either Chicago airport. That is your best option in my book.

ENJOY!