We have lived in North County for 4 years now, and my advice to people is always to try and stay close to the activities you want to do. San Diego Zoo/Balboa Park, Padres, USS Midway are all downtown. Not a bad drive from La Jolla/Mission Bay, but a good hour from Oceanside/Carlsbad/Encinitas if traffic is normal, and can easily get up to an hour and a half. The last thing you want to do on vacation is sit in traffic for an hour and a half each way to get somewhere.