We were in Shanghai and Beijing for the first time in July - and it was very hot, humid and smoggy then. Still, loved Shanghai...Beijing, not so much.
Thought that Shanghai was a very accessible city, despite its size and growth. There are still distinct neighborhoods, it's quite walkable and fairly easy to get around. We also stayed at Le Royal Meridien, and liked its location a lot. BTW - the Shanghai Museum is quite nice - we spent a lot of time there. Heard that the Urban Planning Museum was nice as well, though we didn't get there.