Luggage and bags:
Roll-along bags work well. A sling backpack is pretty common too.
Clothing/Shoes/Weather Gear: There are nearly 300 sunny days annually in San Jose. Unless you're here for a convention, business meeting, or other professional reason, I'd go with jeans, T-shirt, shorts, and a light jacket or sweatshirt. Our days aren't excruciatingly hot, so swimsuits are needed only during a few extreme hot days in July or August. If you want to dress up a bit more, I'd go with khakis and a button down or polo shirt. Anything more than that and you might look out of place. We don't dress up for the movies and people usually come as they are.
Toiletries and Medical Supplies: Typical necessities but there's drug stores all over the place for things you may have forgotten at home.
Photo Equipment: A digital or regular camera. If you don't want to look like a tourist... PLEASE... Don't take pictures in the mall! It's a dead give away.
Camping/Beach/Outdoor Gear: towel, swimsuit, sunglasses, hat
Do both sweaters and t-shirts as temperatures fluctuate greatly throughout the day.
Photo Equipment: These days everyone has a camera phone, and there's not much to take pics of in San jose but if you're venturing out of there and are taking a roadtrip down the coast, definitely bring a better camera. I brought both a camera and my old polaroid camera to capture stuff in different perspectives. Also brought a tripod in case no one is there to take a pic of us.