Have you had a chance to talk to any current students in either institutions? Both the MD/PhD students in Stanford & NW as well as the grad students in the specific labs you want to join? This might be helpful.
Beyond the career development factors, where would you like to spend your next 7-10 years? It can't be stated enough - you have to enjoy the city that you spend your 7-10 years at. It can't all be about the work/career.