Why visit Mongolia?
For most people, there won't be one big single reason to visit Mongolia, the way one might go to East Africa for the wildlife or to the Great Barrier Reef for the diving. I went to Mongolia largely because my aunt was working there for four months.
But I found Mongolia had an excellent mix of attractions. There are great hiking opportunities, varied and sometimes spectacular landscapes, and a good range of wildlife and plants. There are "exotic" herders and ex-Soviet block infrastructure. And there's history — 1200 year old tombs, 300 year old monasteries — art and architecture, and so forth.
Throw in the world's only wild population of Przewalski horses, and the attraction for horse-lovers is obvious.
Areas we didn't see at all included Hustai National Park (with the Przewalski horses), Western Mongolia (with the high peaks of the Altai), or Eastern Mongolia. There was plenty more walking to be done in Khovsgol or Terelj or even in Bogdkhan Uul. And there were even sights in Ulaanbaatar we didn't make it to, though we spent quite some time there.