I was in Mongolia for around two weeks; went camping and stayed a little too long in the capital (I was waiting for others to share expenses with for camping). I wanted to visit more places, but it got way too cold and didn't have enough time, maybe I'll return during the warmer months in the future.
There's a lot of things to do in Mongolia even if you only have a couple of days. Ulaanbaatar has a couple of museums, memorials and a viewpoint to pass the time before camping or on your way out of the country. It's a fairly developed city with malls, restaurants, local markets, shopping centers and movie houses. I found the food and movie tickets cheap! It's easy to navigate even if you don't take public transportation; I walked to everywhere most of the time. The accommodation where I stayed in had a central location for attractions in the city.
If you don't have much time, a day or overnight trip toTerelj National Park is a possible inclusion to your itinerary.
You can include a trip to Chinggis Khan's Statue along with Terelj.
Camping
You go to Mongolia for one thing --- to enjoy the great outdoors! That's exactly what I did during my stay, I was only able to explore the southern part of the country (the Gobi Desert area and destinations towards it).
It was an unforgettable trip with great company. We drove through the countryside and saw the landscapes transform and the weather change; from steppes to desert to snow as far as our eyes could see.
The stops we went to during the camping trip were (I included links to the names if you want to read more about them):
You can add or remove destinations on your itinerary, it is customizable. You'd have to agree about the inclusions with the group you're joining. I booked a tour with UB Guesthouse, the arranged everything; transportation, food, lodging, etc. You can do it on your own, but you'd still need to rent a car if you don't have your own vehicle or bike.
Best Time to Visit
Ideally, the months from June to September are not as extreme (in terms of weather) as the others. Summer (June to August) sees the most visitors, you'll see plenty of tourists camping and heading to other parts of the country by bicycle, motorbike, hitchhiking, etc. I visited Mongolia towards the end of autumn and the beginning of winter around November (it snowed the day I left Ulaanbaatar and in the Gobi Desert).
The group I was with was almost always the only tourists in the sites we visited and the camping grounds we stayed in. I barely saw other people while we drove to our destinations. At that time even the nomad families have settled somewhere for winter.
Where to Stay
I would recommend UB Guesthouse for both accommodation and tours. You have other options during your stay. A bed in the dorm costs around US$8 a night (approximately Mongolian Tughrik (MNT) 20,000). A single room is around US$20, twin room is US$22 and a double room is about US$25 night.
What to Wear
During my visit (November) temperatures dipped below zero even in the morning. I had to wear layers to stay warm throughout the day. You can war light clothing in the summer, but still bring a jacket with you for cold nights.
How to Get to Mongolia
The route I took was from Beijing to Jining Nan to Erlian to Zamiin Uud to Ulaanbaatar. You can read more about it here:Crossing the Border from China into Mongolia.
Expenses
Everything's in Mongolian Tughrik (MNT)
Conversion as of this writing is US$1 = MNT2,500
1000 - Bus to Zamiin Uud from border
38050 - Train to Ulaanbaatr from Zamiin Uud
256540 - Food
14500 - Transportation (within city)
100000 - 5 nights UB Guest House
15000 - Laundry
2500 - Towel rental
8000 - Entrance fee for Bogh Khaan Palace
23100 - Postcards
8000 - Entrance fee for National Museum
12000 - Movie ticket
962500 - 7 days Gobi Desert trip (around US$55 a day)
10000 - Tip
5000 - Fee at Zamiin Uud border
1,491,290 - Total
My biggest expense was the camping trip; overall Mongolia (even the capital) is a cheap country. I ate decent meals with generous servings and had plenty to spare for dessert. I saw a movie in 3D for half the price I would normally pay for back home (really cheap!). Imported chocolates were cheap too.
You could arrange the tour on your own, but you'd have to form a group to share expenses for the car rental. There are public buses that go to the nearest towns for the places you may want to go to. However, it's going to be difficult to do trips on your own during low season.