Shanghai is blazing hot during the summer but it is also very damp and cold during the winter. For this reason there are few if any hotels with outdoor pools. In your situation, I'd stay at the Hilton on Hua Shan Road. It's centrally located, walking distance to fantastic restaurants and the French Concession shops/streets for walking and offers a decent level of service. The Hongqiao Hilton is too far away to be appealing unless you enjoy cab rides to get anywhere interesting.

Another choice would be the Intercontinental Puxi. It's definitely not in as nice an area as the Hilton but it is only 3 subway stops away from People's square and the actual facilities are better than the Hilton with an entire building devoted to executive floor guests and a fantastic lounge for breakfast and cocktails. I stayed there over New Year's and as a Plat got a 1 bedroom suite with soaking tub. Staying in Pudong is akin to staying in New Jersey.