House Or Rental
This is a good option when it comes to accommodations. If you plan well ahead the owners maybe willing to give you discounts. This maybe a better option than hotels. If you will be renting, good areas to rent are Clairemont, Bay Park and Pacific beach/Mission beach area
Flight
Some airlines offer great deals for groups. Please contact them and see if you can get a deal. The closest airport is the San Diego International Airport.
Flight
This airport is 2 hours drive from San Diego, it's a good option if you would like to have a road trip. There are buses, trains and rental cars to come down to San Diego