New Years' eve at the Marriotts was a great experience at a very reasonable price that included a wonderful Sunday brunch. What a deal!
All the employees were friendly, corteous and always looking up for you.

This Marriott hotel is a sprawling complex with the rooms spread out. But there's a lot of directional signs so you can get your bearings whenever you take a wrong turn to/from your room. They usually attract the convention market so it's usually busy. They have a courtesy shuttle to and from SFO/Bart that you don't have to worry about getting a rental car right away, unless you have to do trips outside the city. Although they charged us $20 per day for parking which I found a bit steep considering we're in-house guests.

For a quick shopping fix, there's TJ Maxx, Ross, Rite Aid and Trader Joe's within walking distance. They also have a shuttle to the nearby malls or San Mateo downtown and other areas within a 5 mile radius from the hotel.

I stayed at the San Mateo Marriott recently for a business trip. The rooms and service was excellent. Since I was part of a larger group I even got an extended check-out. The TJ Maxx and Russo shops near by are good to do some shopping.
The hotel is well connected to the SFO airport by an hourly shuttle and this was very helpful since I was coming over from India.
The gym is more than adequate - both cardio and strength training is covered! The beds and bathrooms are terrific. The staff is polite and helpful. I have had a very good experience staying here and would gladly recommend it to anyone visiting San Mateo for business or personal reasons.

This full service Marriott happens to be conveniently located for the airport and my business destinations.

The rooms are comfortable and spacious, with plenty of room for working at the desk. There is a pool, fitness center and a lively bar/restaurant. I used the concierge lounge for breakfast, which was amongst the best I've seen in similar places in the US (I mean.. smoked salmon?!).

Some negatives, all of which are minor in my view -

My room was a little noisy, mainly due to leakage through a door to the adjoining room. The Internet connection was not great. The layout of the hotel is rather rambling; I've stayed a few times and always seem to be a long walk from elevators and I've never yet got a room on the concierge levels even though I have the appropriate Marriott status. The restaurant is nothing to write home about; I would say the menu over-promises for lack lustre, regulation hotel food.

Other reviewers have noted the parking charge. My conclusion is that if you're staying here on business, don't rent a car. The hotel has a free airport shuttle, and 1 per hour is fine going to SFO (though I wouldn't want to wait for it on arrival). Also, the rental car garage at SFO is badly located (long train ride from airport, no gas station handy). You ought to be better off with taxis (I had no problems at the hotel, although I did hear there can be a shortage at peak times).