I stayed at the Marriott Rivercenter for a conference (Sunday night-Friday), so I was able to get a good feel for the hotel. Overall, everything was great. I would have rated it a 5 of 5, but the front desk did get one of my wakeup calls off by two hours and was also a little rude at check-in, so I couldn't give it a perfect score.
As previous reviewers stated, the location is ideal for San Antonio and the Riverwalk. You can walk out of the hotel and there it is. Also, a short one block walk to the Alamo. It's connected to a shopping mall and walking distance to bars and restaurants. Our company (500 or so) made Beers and Steers the "hangout" afterhours. The downstairs is a restaurant/bar and the upstairs had nightly Karaoke. I don't know if it's normally that popular on weeknights, but it certainly was "The Place" for our group. The food and service at Beers and Steers was very good downstairs and bar service about as well as can be expected upstairs with a packed bar and only one bartender.
As for the hotel, most all of the staff were very friendly and helpful. I did have a young lady checking me in on Sunday evening that was a little rude. We were forced to have roommates in the hotel and didn't know who we were rooming with. I asked who my roommate was and if he had checked in. I received a "I can't tell you that information" answer. Having done this roommate routine for ten years at numerous hotels, I have NEVER had someone not tell me who I was going to be sleeping three feet from and sharing a bathroom and shower with. Like I wasn't going to find out or something? Obviously, this was a little ridiculous.
Our service and food at the hotel and bar ("The Bar", on the lobby level) was excellent, with no complaints.
We had a great meal and dining experience at the nearby Chart House Restaurant. This is the revolving restaurant at the top of the nearby Space Needle. I believe it is 75 stories up. There is also an observation deck. I will have to say that the service was very slow, so block off a lot of time. For a romantic dinner or special occasion, I can't imagine a much better choice. People in our group all had good success with the various seafood, fish and steak entrees. The Charthouse is a chain and their Lava Cake dessert is one of the best desserts many of us have ever had and is one of their specialities. I've been the one in Alexandria, Va and both have been fabulous.
Regarding transportation, I really feel like you can go without a car at this hotel. Because of it's close proximity to the RiverWalk, taxis and public transportation, you really don't need one. There is a Trolley ($1 each way) that takes you to Market Square, which I'd also recommend. That particular Trolley line (Yellow) runs every 15 minutes until midnight. They pick you up across the street from the Denny's, which is right by the hotel. There is a Farmers Market, at Market Square, shopping and a few restaurants/bars there, also. We ate at Mi Terra (sp) with a good meal and Margaritas and some others in our company ate at some nearby restaurants, with good reviews.
There was not wireless internet in the room, but they did offer high speed internet for $9.99 per day. Because of the size of our group, they didn't charge us for that. Taking a tip from another reviewer, I did request a refrigerator for the room. I also had the pleasant surprise of finding out the hotel offers complimentary bottles of water, that we were able to put in the fridge. They said they don't openly tell the guests (probably because they would go through thousands of bottles of water daily), but that was a good find. They also brought up some bananas later in the week. I think it could have been because of the tip I gave the first guy who brought us water. :-)
The Alamo is a quick walk from the hotel and is definitely worth the visit. At night, when it's closed, it looks TINY. During the day, you can walk through for free. To get the audio tour, I believe it's a $5 or $6 charge. We would have done the audio tour, but didn't have enough time. They also offer horse drawn carriages at night outside the Alamo. I thought it was a little high ($15 per person). I asked for a little "volume" discount for four people, but was denied--still $60. Oh well. They didn't get our money.
Overall, I'd highly recommend this hotel and stay there again if I'm ever in San Antonio. Our company took care of the rooms, so not sure about how much they are or what deals are available.