I've looked into this before and it is complicated. The zone which includes SW goes well north. There is one over Balboa Park where the zoo is but there are not nice hotels there.
Hotel Circle has its own zone, and this has chain hotels including decent ones like Sheraton and Marriot. This is a good place to bid on for it's high star rated locations. It's about 15 minutes from parking lot to parking lot of the Zoo or SW.
If you want a really nice hotel you need to bid on Downtown San Diego that has Hiltons and an Omni, and this may put you 20 minutes away.
All these areas are close but traffic can make the drives take longer even though they are no more than 5 miles away.
When you go to bid you can see a map of the locations