I am intrigued in this Torch Lake. I will be looking into it. I am also looking at hitting some in Minnesota. Not sure what Iowa has to offer, but I'll look there as well. As for Illinois... well, they all come up here so I imagine there isn't much.
I hear Lake Okeboji in North Central Iowa is amazing. It's not impressive from Google Earth. But from what I can tell, it's got a dense population of lake homes, and a lake chain with bars and places to eat. That's a combination of a real lake party. (if that's what you are looking for)
Lake Pepin from Hastings all the way down to Wabasha and Winona is supposed to be incredible boating. There are some of the biggest boats in the state on that body of water. It truly is a place to spend multiple days with many marina options. I could handle that, as it would open us inland lakers to something that would require real navigation.
A bucket list item would be the Apostle Islands around Bayfield too. Now that we have a decent sized boat, it would not be out of the question to go explore if the weather cooperated. Any place in MN with a "chain of lakes" is a great destination, as there is so much to explore. It's not like dropping into a small round pond that you can see all shores. It makes you want to go explore. Alexandria area, and Brainerd, or the Whitefish chain all come to mind first.
But there are so many with a simple deep stream connecting, and with a tip down tower, or no tower, you can navigate very easily. Others have quite large river systems with no issues at all.
My wife and I are on a mission to explore more lakes this season. We used to back in the day as lake gypsies. Now with a lake home we rent per season, the boat sits on a lift. But I want to go out of my way to pull it at least every other week and go explore. There are just too many beautiful places not to see a few more. We are 45 minutes from the heart of the Detroit Lakes country. We may even find our retirement home. As that is my wife's mission. But I want to spend at least one day on the lake we settle on.
It truly is the land of 10,000 landings and Sandbars. Nothing better than floating up to fresh faces and sharing common interests.