Located in the center of downtown San Jose, the Tech Museum (of Innovation) is worth a visit. The San Jose Marriott is a very short walk from here. The Museum is very much hands on, and has the added benefit of being heavily funded and supported by the titans of Silicon Valley. So even the IMAX theater is better than most to which I have been.
Good for an afternoon alone or with the kids. Like the nearby Computer History Museum the Tech is a great place to spend a few hours.
After Museum time try Habana Cuba Restaurant for a nice intimate Cuban dining experience. One of our favorites and worth finding in downtown San Jose. Anytime except when the Sharks (NHL team) are playing and then it might be hard to get a table.