I booked with Mongolian Vision Tour a 2 days tour. It consisted in seeing the Zeisan monument in Ulaanbaatar, then the Genghis Khan statue, sleeping in the yurts of a nomadic family, and the second day going to the Terelj National Park to see the Turtle Statue and a monastery built in the nineties.
This tour was great, especially the night I slept in the yurts. The family was nice and made really good food for us (we were 2 with another tourist) for lunch, dinner and breakfast. The place was amazing, perfectly located in the middle of nowhere with nobody around us for several kilometers. But still 2h driving from Ulaanbaatar. We had a horse riding too as the family takes care of horses and cows. They really share the way they live and it was great to have the opportunity to discover it. The other activities were ok too but definitely the best is to stay sometime in the area around the yurts where I slept. And the tour is organized to let you taking your time there, which was something I really appreciated.
The guide (Sonya) was really nice, helpful and still ready to share information and answer to questions. She stayed with us all the time, she even slept in the yurts too. Everything is organized and you have nothing to think, only look at landscape and discover.
Price is not cheap, but I think it was on the average in comparison of tours organized by other travel agencies in Mongolia.
I highly recommend this tour if you stay a short period of time in Ulaanbaatar, for instance during a Transsiberian / Transmogolian trip as I did.
Thank you for giving me those unforgotten memories!