Hangzhou: find somewhere near (or on) the lake, if you are keen for a scenic walk. West Lake is renowned for its beauty and history.
Last visit I stayed at the JW, which was a bit of a hike to the lake. Stayed at a Hyatt on the lakeshore a while back: great location. Drinking spots? Hit the lake, find a place to sit that sells cheap local beer and watch the locals walk by.
Can't help you with Tianjin, haven't been there for many years. If you are there for an extended period, you might want to consider the high speed rail for a day trip to Beijing.
Enjoy