I have been hoping to see more responses to your inquiry. I am new to Houston and need to find out which are the best eateries. I saw an ad for the post oak grill in association with this event. Don't know if it's good but the ad looked yummy
Post Oak Grill is a good choice. I have never been during restaurant weeks though. I like the cozy upscale atmosphere. The food and service are excellent. If I had to choose though, I'd go a few steps up with the Capital Grill.
Otherwise, I love great seafood such as Truluck's. The last time I went on a date there, the tab was a little over $400 including all courses and a fine bottle of wine.
If I want a great combination, I like Del Fesco's for their seafood platter as an appetizer and an amazing steak for the main course with a great collection of fine wines.