My favorite is the Santa Clara Marriott. The location is central to the Silicon Valley, close enough to McEnery and Santa Clara Convention Centers and great for a family especially if you're on business as the family can have fun at the pool or at Six Flags nearby.
If you have a booth to setup and manage at McEnery, or a Hospitality Suite to run, the San Jose Marriott maybe the most convenient. (I know people who have done that) If you can delegate, want to avoid the crowds and/or prefer a more private - by invitation only - setting for a Hospitality Suite, then the Santa Clara Marriott is worth serious consideration.
Except for San Francisco, it's nearly impossible to be in the Valley w/o a car and I prefer self-parking which is less than $10/day - which is very reasonable for the budget-conscious. With Intel nearby, there are enough WiFi hotspots to connect to for free (IBahn is about $12+). I haven't been there since 2009 changes, so best to check upgrading and the Concierge Lounge - which ~was/is~ among the nicest I've experienced.
I stayed at the Santa Clara Marriott every week for 6 months and highly recommend it! Although its been quite a while since I was there, the people at that property were just marvelous!
Rosalita (if I recall her name correctly), the wake-up call lady, was just a doll.... every night we'd chat for a few minutes when I put in my wake up call and every Sunday there'd be a special personalized 'welcome home' message from her on my TV asking about my weekend. I finally had to go to the front desk just to meet her in person! The front desk takes pictures of their favorite guests and post them in the office with the guest's name so everyone can refer to you by name. My waiter in the restaurant would always sit with me while I was having dinner... just to chat. The ladies in the CL would always give me a bottle of chardonnay to take back to my room each night. In fact, when one left for another job, she even sent me a post card letting me know how she enjoyed her new job! And, when I finally bid farewell to them, they presented me with a huge basket full of bottles of my favorite wine, pasta, pasta sauces, bread sticks, cookies, etc.!
And, it is within 20 minutes of San Jose!