SanDiego1K

Try to find a hotel where you can stay within walking distance of a trolley or Coaster station. The Coaster goes north to Oceanside. Amtrak goes north to Los Angeles and then on to Santa Barbara. I recommend taking Amtrak to San Juan Capistrano one day. You can walk from the train station to the Mission. It's one of the most interesting California Missions with its exhibit of the various trades the padres taught the Indians. On the far side of the track is a block of restaurants and shops. One Coaster and trolley stop is Old Town, where the Old Town State Park is along with lots of Mexican restaurants. There are lots of things to do downtown within walking distance of the Amtrak/Coaster/trolley station including a harbor cruise and the ferry to Coronado Island.

Poke around at this site and see what you learn. Hopefully if you search (or someone more knowledgeable than me comes along) you will find a better resource that talks about sightseeing available at each Coaster and trolley stop. Places where you'd need to take a bus/Uber are Balboa Park and downtown La Jolla.

I'll keep thinking about a specific place to stay near a trolley stop. You do have all the options of downtown San Diego, the hotels on the water along the Convention Center, where you can walk across the street and get on the trolley. Consider the Hyatt/Marriott/Hilton line up there. Should you want that area, choose a hotel between the Convention Center and Seaport Village for ease of walking over to Seaport Village.