Divebums - A San Diego Dive Website is a good starting point for just about everything related to diving in San Diego.
LaJolla Cove is the signature shore dive. On Saturday morning plan to get there early - there's going to be a lot of divers and not many parking spaces anywhere near the cove. It's only about 15-20? minutes north of the Hilton.
LaJolla Shores - which is likely where Power Scuba is diving - has a bigger lot.
One option is to pick up tanks the night before at
Sport Chalet near Mission Beach. They won't be open real early.
On
your dime the area west of Sport Chalet is called Hotel Circle. That name or Mission Valley will be in most of the hotel names. Lots of stores/restaurants in that area also. Here's a partial list of what's in that area from google maps.
Comfort Inn
Doubletree
Kings Inn
Motel 6
Travelodge
Days Inn
Best Western Seven Seas.
Sheraton
For boat trips they often dive the Kelp fields off Point Loma. It's one of the more interesting dives you can do in SoCal. Just don't try to surface in it - stay under until you can surface in clear water if possible. And there's a wreck alley just off San Diego. There's also Los Coronados Islands - not to be confused with Coronado Island in the bay. They're a boat ride - maybe 90 minutes - south of San Diego and there's a seal rookery there that can be a lot of fun. Not very deep either.
Another boat with a good reputation is Lois Ann. All of the options are listed at the bottom of this list:
California Dive Boats : The Official Page
One really convenient thing for you might be the Humboldt/Waterhorse Charters or Lois Ann since they both leave from the Quivera Basin area in Mission Beach. Do notice that Seaworld is just across the street also...lol. The Hilton is in the upper right corner of this map.
On almost every boat the DM stays on the boat. If you want/need a guide that's extra. Tanks/weights are generally provided but specify what you need when making reservations since a lot of local SoCal divers bring their own.
You'll need some exposure protection - water off San Diego in April averages about 60 degrees. Scroll down this chart to Scripps Pier - that's in LaJolla.
https://www.nodc.noaa.gov/dsdt/cwtg/spac.html