Also, a reminder to consider the Omni Hotel for your SD stay. The Omni is connected to Petco by a skybridge that is for exclusive use of hotel guests - some rooms have (partial, peripheral) stadium views (plus, if you have a rental car, you don't have to pay a second parking fee at the ballpark). Besides it's proximity to the ballpark, it also happens to be a very nice hotel.

Most Gaslamp and Convention Center hotels are also a relatively easy walk to Petco.