Inner Mongolia is Myrtle Beach. What I mean is, if you have the time and budget, you’ll probably go to the real-deal: Mongolia and Tahiti (or somewhere else more exotic than Florida).
That’s not to say Inner Mongolia is not worth your time. I just feel it’s not as authentic as Mongolia since it’s within the borders of China, and hence, there are lots of Han Chinese farmers who aren’t actually nomadic Mongols.
My time in Inner Mongolia was a lot of fun: spent a night in a yurt, horse-backed, visited a couple Tibetan temples (which you wouldn’t find in Mongolia), and sand-surfed on the fringes of the Gobi Desert.
Basically, if you’re taking the grand tour of China and want to get a glimpse of Mongolia, or want something to do that’s close to Beijing (it’s six hours away by bus or car, and a short one hour flight away), Inner Mongolia is a good bet.