The Sheraton Overland Park is the closest to the Sprint campus and is a relatively new, modern hotel with very nice suites.
The Crown Center is in mid town and across the street from the renovated Union Station. The Crown Center has had its' glory days in the 70s and 80s when the Royals were competitive and Oleta Adams ruled the bar downstairs. I agree that it is dated but I do not see this property becoming a "modern" looking Westin anytime soon.