The Schizophrenic Hotel
The Houstonian needs to decide what it really wants to be when it grows up - one that emphasizes the quality of individual guest experiences, or one that wants to cater to large groups such as weddings and conventions. Right now it is trying to do both, and the result is a generally poor experience if you are a couple or or a single looking to spend a few days in a really nice hotel.
The Good News: The Houstonian's grounds are pretty (although not as beautiful as they are made out to be on the official site). The staff is attentive, especially in the hotel's restaurants and bars, and the food in the restaurants was excellent. The rooms are quite nice.
The Bad News: My wife and I stayed in the hotel for five nights, and on each and every day a large group was also staying. These were mostly weddings or conferences. As a result:
 - It was almost impossible to get an appointment for treatments in the spa, which was a main reason for going. We were told - only after we arrived - that it was very difficult to get appointments without scheduling well in advance. Even as a hotel guest. The spa is very popular among local Houstonians.
 - While a stay at the hotel provides access to the health club, it is also apparently the place to see and be seen on the health club circuit in Houston. Free classes (for example yoga) are difficult to get into a packed when you do. The workout/weight area boasts almost 800 machines... almost all of which were occupied early on a Saturday morning. 
 - Every night but one was punctuated by loud and occasionally drunk guests cavorting in the halls of the hotel.
 - Parking at the hotel, should you chose the "self park" option, is difficult, due to the number of party-goers or conferees.
 - Room service food was consistently bad.
The title of this review is somewhat misleading; in fact, the Houstonian seems already to have made a business decision that emphasizes catering to guests associated with large events that occur in the hotel. They have also decided that the income derived from those other than hotel guests at the spa and health club is more important than the experience of the hotel guests. These may be sound business decisions, but if you are looking for excellent individual service at the Houstonian, you need to be aware that your needs will come in a distant second the needs of the larger groups who are undoubtedly laying out more money.