Agree, there's no need to stay in Pudong at all. If you do, stay around Century Avenue metro station, which gives direct access to Puxi and the Expo (on Puxi side).

A week in Shanghai seems too much. 3 days for the Expo as well. It depends on how many pavillions you want to visit, but I'm planing for an upcoming private trip one evening ticket and one full day ticket, not more. Furthermore, you say in your other thread that you're going during the October holidays which might not make the Expo a very pleasant experience. You should pre-purchase tickets (ask the hotel) as these are "special" days with higher prices and more people expected than on other days. Edit: Just re-read your post and saw you're going in September, so never mind...

Hotels in Shanghai: Certainly no luxury property, the Le Royal Meridien at People's Square seems to fit your bill well - book a more expensive room or suite with a view - location, as moondog said, is as good as it can get, with immediate metro access. (The Sofitel Hyland is close and in a good location as well).

There's the Radisson New World as well - a solid 4 star hotel with fairly small (standard) rooms - but absolutely no 5 star or even luxury property.

If you really want to spend a couple of days at the Expo, I would probably look into the InterConti Expo, which is close to the Expo site (and to nothing else) with a shuttle service and -according to reports here- with very decent rooms. The hotel is incredibly expensive, compared to other upper upscales.

Spectacular, but in less convenient location and totally overpriced is the Park Hyatt - and I wouldn't stay there on a paid stay; neither at the Grand Hyatt.

The Peninsula is an excellent location for Nanjing Road with fabolous views, but there's no metro access and I would, hence, give it a miss when you plan to use the metro.