Crankin, what part of town? I can ask for recommended rides for you.
DH just rode from our house up to Oceanside and back today -- about 60 miles. There are long stretches of highway along the ocean that do not have lights, but there are city areas, too, that do. It's a favorite route of the local bike clubs, though, so you'll be one of many people on two wheels.
I like to ride the 7-mile to-the-turn-around-and-back loop MUP at Lake Miramar, which is just off I-15 across from Miramar MCAS, and around the four-mile-shared-with-cars-and-trucks route around Fiesta Island, which is right in the middle of Mission Bay, off I-5 at Sea World Drive. Both have beautiful water views.
There is a bike path near Fiesta Island that runs along the San Diego River that goes all the way to Ocean Beach. A lot of it is designated bike path, although you'll find runners, too, and when you get into town, there are lights.
There's also a sidewalk that goes all the way around Mission Bay - several miles, not sure how far exactly - but it has an 8 mph speed limit and lots of pedestrians, bladers, boarders, and other bikes, especially near the parks. It's pretty, though, if you don't want to go fast.
The mountain highways are really great for hill practice. I'm not strong enough to tackle those yet, but I hear they're beautiful, and right now it's cool up there. There's snow down around 6,000 feet, I think.
Let me know what area you're interested in, though, and I'll ask for some routes for you.
Roxy
Getting in touch with my inner try-athlete.