I've probably seen a zillion vacation possibilities in Missouri and Illinois so it's frankly kind of hard to impress me. This new Mt. Sterling place managed to do the impossible mainly because it has a very sweet private lake.
There's nothing quite like falling asleep when you have the Mississippi River nearby. If that's also on your list of "things you'd like to experience on a getaway", I found a place in Hamilton, Illinois that offers that and also an orchard view.
Sometimes to figure out where you're going, you need to explore where you've been. There is history available to explore in southern Illinois at a secluded cabin that happens to sit along the Trail of Tears in Shawnee Forest.