Hmmm, a map might be of use. Oceanside is 45 minutes or so (depending on traffic) from downtown SD. Rather than Oceanside, I suggest you look into Coronado.
Of the other places you mention, La Jolla is the furthest from downtown althoughh it has a nice village feel to it. The good beach at La Jolla (the Shores) is a couple of miles away from the village.
Ocean Beach has a funky, slightly hippie vibe.
Are you looking for a hotel room? Renting a house? What's your budget per night and how many rooms are you looking for? How long are you staying?
A bit more info will help the SD locals pinpoint the area best for you.
I also suggest Coronado.
I am hoping to rent a condo or house. I'd like to keep the price around $1500-$2000 for the 5 night stay for 6 adults.
check out vrbo.com for homes/condos - specify but typing in coronado, la jolla or whatever area you decide on. just so you are prepared...in california, june is often known as "june gloom". you will likely run into days where the coastal area is overcast/foggy in the mornings. it usually clears when it starts to heat up but you might want to plan on activies in the morning and enjoying the beach areas in the afternoons.
Thanks for your help.