Lake Location
Lake location is probably the most overlooked factor when it comes to finding the right lake. The 20 minute drive on the winding roads through the woods is beautiful the first 10 times you do it. After that it gets to become quite the hassle when a "quick" trip ends up eating two hours of your day, 40 of which are driving! The further you get from town the less time you will have to spend with your family.
Another reason lake location is important is that proximity to town, especially a big town, greatly increases the chances that you'll have what I call the modern amenities. High speed internet and cell phone coverage are important to a lot of people. With the abundance of state land and the relative lack of a year round population, there are many spots in Northern Wisconsin where you won't have cell phone reception or high speed internet.
The last modern amenity that is related to proximity to a bigger town is natural gas. In the winter it gets cold up here. Even if you won't be coming up for the winter, you still will be keeping some heat in your house. Natural gas is significantly less expensive and more reliable than heating with propane.