For a current list of ramp conditions, fees, and exact locations, see: The FishingNetwork.Net's list of SoCal Private Boater Launch Ramps. Following are some comments about which ramps to use when...

All public marine launch ramps in the San Diego area are free, with free parking, except for the ramp at Oceanside. Oceanside charges a parking fee if you want to park near the ramp.

In general, all ramps are in good condition, and most, but not all, have ample parking. The only ramp with washdown facilities is Oceanside.

None of the public ramps have associated campgrounds, but most have hotels / motels nearby, and most allow self-contained RVs to park overnight. In Mission Bay, Campland-on-the-Bay is a large private campground with its own ramp. It is on the northeast side of Mission Bay, which puts it a few miles away from the other Mission Beach ramps, and about a 15 minute drive from the Shelter Island launch ramp in San Diego Bay

San Diego Bay

General
San Diego Bay is the closest launch area to Mexican waters. Its entrance faces almost due south, so it offers the safest departure/entry when there are big swells from the west or northwest. It also does not have restricted speed areas in much of the bay, allowing for speedier exit and entry than Mission Bay to the north, which is restricted to 5 mph speeds throughout much of the bay.

• Shelter Island Ramp - Near Lindbergh Field
  Shelter Island is the closest launch ramp to the Mexican Border, and as a results, gets hit heavily during the prime fishing months. The ramp, although wide and in great condition, is enclosed by a verrrryyy small turning basin, making launching and retrieving your boat in crowded conditions at low tide a white-knuckle experience. Because of the long lines during peak season, you may be better off going to one of the other SD Bay ramps, such as J Street in Chula Vista, or the Glorietta Bay launch ramp near the Hotel Del Coronado, and making the longer run to the ocean. Another possibility is to launch in Mission Bay and make the run from there
  
  
• Glorietta Bay Ramp - Coronado Island
  A 2-lane ramp located next to the Coronado Aquatic center and the fabled Hotel Del Coronado, this ramp is usually uncrowded. Parking is limited to about 12 vehicles with trailers. This is the next closest ramp in San Diego Bay to the harbor mouth, but because of it's size, many people pass it by. Also a good access point for people fishing San Diego Bay itself. Adjacent to the Glorietta Bay Marina, which is a full service facility with rental skiffs.
  
  
• Bayside Park Ramp - National City
  This is a nice ramp, but it has restricted hours of operation (sunrise to sunset, locked gate). Not a popular ramp with fishermen unless they are taking a short daytime trip.
  
  
• J Street - Chula Vista
  This is a nice wide ramp, located next to the Chula Vista Marina, which is a full service facility with fuel and rental slips. It is also the furthest away from the harbor mouth, requiring about a 15-minute run to get to Shelter Island.
  
  

Mission Bay

General
Mission Bay is man-made - if consists mostly of dredged marshland - but it was built with marine recreation and vacationers in mind. It has a multitude of launch ramps, separate areas for water skiing and PWCs versus sailing and fishing, a campground, lots of hotels and motels, Sea World, and is in close proximity to the San Diego Zoo.

It is only about 8 miles further north than San Diego Bay, so during peak season it is often faster to launch at Mission Bay and run south, than it is to fight the crowds at Shelter Island. There are two major drawbacks for fishermen: speeds are restricted to 5mph in the areas not set aside for waterskiing / PWCs, and the harbor entrance faces due west, making it a bit more risky exit/entrance when there's a big west swell.

• South Shores - Near Fiesta Island
  South Shores is an outstanding ramp - brand new, wide, large mooring docks, well lit, lots of parking. It's only drawback is that is about another 15 minutes (at the harbor speed limit of 5 mph) east of Dana Landing, which is the closest Mission Bay ramp to the harbor entrance
  
  
• Dana Landing Ramp - Just past Sea World
  The closest ramp to the ocean, Dana Landing is the most popular ramp with fishermen. It is not that wide, but it has lots of parking, a deli/market next door, and a West marine Express a few stores down. It is also the meeting point for several guide companies, including Bowman Bluewater Guides and Outfitters, Paradigm Shift Charters, and Stock Charters
  
  
• Santa Clara Point Aquatic Center - on Santa Clara Point in Pacific Beach
  The Aquatic Center launch ramp is tiny - really suitable for just one boat - and the parking is nonexistent if you get there too late in the day. But if you're deperate for a launch point, it's worth checking out.
  
  
• Ski Beach - Across the channel from Dana Landing
  This ramp is a sleeper. Width with easy access, it is nearly as accessible as Dana Landing. However, it is popular with water skiers and PWCs, so you will have to fight them in order to launch. But if the line's long at Dana Landing, it's a viable alternative. Not many water skiers out at 4:00am.
  
  
• MB Visitor's Center - Clairemont Blvd offramp, visible from I-5
  Similar to situation to Ski Beach, The Visitor Center ramp is easily accessed fromt he freeway, but is also the furthest ramp from the ocean. However, there is no speed limit on the bay between this ramp and the channel connecting South Shores and Dana Landing, so the actual added trip time is not that bad.

La Jolla Shores Boat Launch Beach

General
Located at the end of Avenida del La Playa, near the La Jolla Beach and Racket club, this beach is a popular launching point for kayaks and cartop skiffs.

Some of the biggest white seabass and yellowtail in the San Diego area are caught from 'yaks and skiffs launched from this beach, which is on the southern edge of the La Jolla Canyon Marine Preserve, and a moderate-length paddle from the fabled kelp beds of La Jolla Point. This is also a very popular dive spot.

Oceanside Harbor

General
Oceanside Harbor's ramp is an anomaly. Unlike other San Diego ramps, parking adjacent to the ramp requires a fee ($10.00 / day), but it also is the only ramp in San Diego with a freshwater washdown area for boaters. Popular with PWC users, however, the washdown area can be hard to get to late in the day.