I second the quality of life in Minneapolis - I turned down "higher" ranked schools for UofM, namely because of how amazing Minneapolis is, both for me and my family (spouse + 4 kids.) And yes, it's cold, but it's also one of the sunniest major metro areas in the US - snow storms blow in and out quickly, unlike the dreary cloudiness of Northeast winters. And spring, summer and fall are gorgeous.
However, if you're going for Chicago Biglaw (if there still is such a thing after the recession/depression), WUSTL does place better - though you'll be competing for slots with the area's big fish (UC, NW) and other Midwest T20s (ND, UIC, Iowa). Many people who go to UofM go there wanting to practice/live in Minneapolis, since it is such an awesome place.
I've heard great things about WUSTL, but I couldn't see living in St. Louis for three+ years, though I know people who love it. Have you visited both places? That might help make the decision easier.