I went to The Mirage for a conference my company was putting on. The conference center itself was nice, with it consisting of a long corridor with different halls. It was kind of confusing finding MEC A-C, but it wasn't too bad overall.
The food and shopping options here aren't the best the Strip has to offer, but the entryway is nice. Also, it's somewhat disappointing that the gym closes at 7pm. Walls are kind of thin too, though the rooms are nice and spacious.