JoJoSungy here - currently residing in DFW metroplex, from the East Bay of the SF Bay Area, born in Chicago. I grew up an Illini fan, but became a Cal fan during my days in the Bay Area. You could call me the reverse Hardy Nickerson except fatter and slower.
I'm gonna break this down into geographic areas and general tips.
-- Silicon Valley
-- San Francisco
-- East Bay
-- General Bay Area
SILICON VALLEY - 45 minute drive south from SF. Santa Clara is in the Silicon Valley. SJC is the airport closest to Levi's Stadium
Transportation: more limited than SFO. I recommend Uber/Lyft or renting a car in this area.
Parking: more readily available than SF
Hotels: kinda pricey...
Food: LOTS of food in the area, but kinda pricey. Korean food is pretty good in nearby Sunnyvale. (personal recommendation: Kunjib - Short Rib Stew https://www.yelp.com/biz/kunjip-restaurant-santa-clara-2 get there early as there is typically a wait list)
Cleanliness: Much cleaner than SF
Things to do:
1. California's Great America - name sound familiar? They have some of the same rides as Six Flags Great America, but I still prefer Six Flags. They share the same parking lot as Levi's Stadium.
2. Santana Row - lots of fancy shops and restaurants to walk around and enjoy
1. If you want to tour Google or Facebook, check and see if they're open to public tours.
2. Santa Clara and the rest of the Silicon Valley often is 10 degrees warmer/calmer/wetter than the rest of the Bay Area. When checking the weather forecast, look at San Jose, not San Francisco.
3. Skip Palo Alto... home of Stanfurd and their taco bell looking campus.
4. BART does not go down to Santa Clara (yet). You'll have to switch to Amtrak if you decide to take a train.
SAN FRANCISCO - SFO to downtown SF can take about half an hour in transportation
Transportation: BART - Bay Area Rapid Transit (SF Bay Area's version of the L) - connects SFO through downtown SF to the East Bay area, MUNI (lightrail and bus system)
Parking: Expensive. Don't do it unless you have to. Uber and Lyft are the easy way to good. Feeling adventurous? Try BART and MUNI.
Hotels: Also ridiculously expensive. Don't do it unless you have to.
Food: Expensive. A bowl of soup will likely hit you for $10+. That said, I recommend taking a peek here for some of the must eats in SF as there are a TON of good options. https://www.7x7.com/big-eat-2019-100-best-dishes-san-francisco-2628689974.html (personal recommendation: Taqueria El Farolito - Super Burrito)
Cleanliness: DIRTY with the exception of touristy areas (Golden Gate Park, Embarcadero, Golden Gate Bridge). I do not recommend open toed shoes as there is a large drug and dung problem on the streets and public transportation stations of SF.
Things to do:
1. Rent a bike - Go around the SF Embarcadero, check out Fort Mason, and/or go across the Golden Gate Bridge
2. Ferry Building - lots of good food stalls and desserts
3. Ride MUNI out to the Sunset district for some good grub. Swing by Golden Gate Park for a bunch of museums. Or take MUNI all the way to Ocean Beach to see the Pacific Ocean. (Note: It's typically cold at Ocean Beach and beware of broken glass in the sand)
4. Union square - Lots of shopping in the area and a skating rink during the holidays
5. Chinatown - this is where you can get food and gifts on a budget!
6. Salesforce Transit Center - there's a nice little oasis on the top floor of the transit center where you can walk around to relax.
Bring hand sanitizer/wipes and a reusable water bottle. California also disallows single use plastic bags unless it's carry out of a restaurant.
Public restrooms are often dirty. Try to seek an upper floor restroom as they're less abused.
DO NOT LEAVE VALUABLES IN YOUR CAR. IT WILL BE BROKEN INTO.
East Bay - 45 minutes Northeast of Santa Clara
Want to see UC Berkeley? It's a beautiful campus on a hill overlooking the SF Bay Area directly towards the Golden Gate Bridge.
Transportation: Take BART to Downtown Berkeley
Cleanliness: DIRTY. watch your step
Food: LOTS of yummy food in the area. Asian Ghetto, Cafe Mezzo, Top Dog, Cheeseboard
Unfortunately, there are instances of crime nearby campus, so stay aware of your surroundings and walk in groups if at all possible.
Wear comfortable walking shoes. Lots of walking. Hike up to the stadium or the Big C and get a really good view of the Bay Area.
The squirrels in the area are kinda aggro but will eat nuts that you may have. make sure you have the unsalted variety!
GENERAL BAY AREA
I won't dive in too deep here, but here are some other spots that are worth a day trip:
1. Napa Valley (about 1 - 1.5 hours North) - for those who want to visit Wine Country
2. Monterey Bay/Carmel (about 1-1.5 hours Southwest) - Monterey Bay Aquarium, Canery Row, 17 mile drive, Pebble Beach
3. Muir Woods (1-2 hour drive Northeast) - good hiking spot if it's not too cold
Please leave any comments if you have any questions! I'll invite my CGB friends to add any insights they may have (I'm not a drinker, so I have no recommendations for bars and that scene)