I travel nearly 120 nights a year for work and this is one of the best hotels for both business travelers and families. The beds are great, gym is above average, and the staff truly tries to make you feel at home. If you have Marriott status, the lounge is fantastic and the employees are always more than accommodating. BJ and Brian are two of the nicest and hardworking guys you can meet. Gary, who does the complimentary "light snacks", (sometimes turns into full meals) makes the best brisket I have ever had.
I definitely recommend staying in the Marriott at City Center. There isn't a single thing I would recommend to them.