If you want to go across the border and enjoy Mexico, try some of the other towns - the San Diego Museum of Railroading in Campo has a very popular day trip via antique steam engine (or perhaps their 1940's diesel) to Tecate, where you can go brewery sampling and shopping without a lot of the Tijuana hassle. Tecate is famous for pottery and some fabrics. And I do think they have at least two zebra donkeys for the tourists to take photos at...
Check at this site -
http://www.sdrm.org/ - for the train schedule. I think they usually run two saturdays a month. The route to get there is also on the way to Tecate, so if you can't catch the train to Tecate and might want to just take the two/three hour back country rail trip, which is pretty nice by itself.
The San Diego Maritime Museum is also very nice. The "California" goes out for a harbor sail almost every weekend, and since the Star of India (the oldest still active tall ship on the west coast) has been refurb'd, she goes out to sail a couple times a year - and you might be able to catch the cruise. The tour of the Star is cool; if you catch it when the school kids have their sleepover and "seamanship training", you can watch them learn how a 19th century sailing crew lived. You can also tour the USS Midway (which I helped decommission ten years ago!)
http://www.sdmaritime.com/index.aspOf course, there's always San Diego Old Town. It is actually a state park, but there's lots of shops and restaurants as well as some of the museums and house tours. The Estulio house and the Whaley house tours are must sees. The Seely stable has a blacksmith that comes in twice a week to demonstrate a period smithy, and from what I understand, they also have a cooper and a carpenter that come in and show period wheel and wagon making.
http://gothere.com/sandiego/oldtown.htmBalboa Park has not only the zoo, but many museums (modern, multi-cultural, natural, technical/scientific and local), art exhibits, artisan's workshops, and art venues. If the San Diego Art museum is a bit pricey on top of the other museums in the park, the Timkin Art Museum is free, and has a great collection of Russian screens and baroque art. Many of the art workshops will have jewelry and other crafts that you will fight tourists for in Mexico. It's a great walk about that can take you most of a day to see everything.
http://www.balboapark.org/Ocean Beach, Mission Beach, and Pacific Beach are very much throw-back sorts of places, very reminiscent of the height of the surfer culture. Sea World is sort of a half Disneyworld, half aquarium. Frankly, if you really want to see an aquarium, check out the Scripps Aquarium in La Jolla, and the Mission Beach Boardwalk, while a bit crowded and hard to get to, has more of a arcade/amusement park feel.
There's a nice botanical garden up I-5 around Encinitas, Quail Botanical Garden. Point Loma has the Cabrillo monument.
The Gaslamp Quarter downtown has lots of little restaurants, a few "hole in the wall historical sites" and shops, and of course - lots of clubs. It's great for people watching.
The Del Mar racetrack is only open for "events" during the winter; home expo events, gun shows, gem shows, computer shows, etc...
There's at least four Indian Casinos in easy distance - Viejas, Barona, Sycuan, and Pala. (yes, I know there are a lot more of them around, but these are the closest I know about that are large) All of them are also concert venues - you might want to check their websites.
If you still want to go to Tijuana, the best thing to do is to drive to a trolley "park and ride", take the trolley the rest of the way down, and walk across the border to the cab station. If you drive your own car, you will be required to purchase Mexican Insurance - and most US rental car companies don't allow you to drive across the border.
Stay on the Avenue de la Revolucion for the most part; there are a few blocks that are well traveled on either side of the Avenue in the central/western portion of the Avenue, but don't stray too far off. The Cultural Center is nice.
I don't know what the going rate for the Cab Drivers are, but most of the ones you pick up at the border cab stand run the same rates.
Good Luck
Haele