I stayed at the Hilton Americas for three nights as part of a conference. The hotel is connected directly to the Houston Convention Center via a sky bridge, and is directly adjacent to the Toyota Center and walking distance to Minute Maid Park. As others have noted, there isn't much else around the hotel, though you can walk to the main part of town with numerous restaurants and bars in about 10-15 minutes. I hopped on the light-rail system there to explore other parts of Houston.
Got a very good government rate on an Executive Floor room that was fairly spacious and included a very comfortable king size bed, clock radio with MP3 input, functional desk area and a large flat-screen TV.
I had access to the Executive Lounge, which is quite large and includes several televisions and a nice view of the Houston skyline. They offer appetizers each evening -- fruit, veggies, cheese and crackers and two hot appetizers that change daily, as well as a continental breakfast in the morning and fresh-baked cookies, water and sodas throughout the day. Also had a turndown service each evening when I received bottled water and a chocolate. Not sure if this is just done on the Executive Floor.
Room service was prompt and the food was tasty, the indoor pool looked nice, and the outdoor deck adjacent to the pool is a great place to watch the sunset or view the city lights. They provide kiosks to print out your airline boarding passes, which is always a nice touch. Gym was smaller than I expected and not really worth the fee -- it should really be free for hotel guests... though it did have a nice view.
My only complaint was that there was an anime convention going on during my stay and the hotel was flooded with people in all sorts of strange costumes who sat in the hall talking loudly until 3 a.m. Reminded me of a college dorm, and all the drunken shouting made it kind of hard to sleep.










