Where to stay in Tibet
Hotels
Hotels in Tibet are mainly focussed upon Lhasa. Lhasa has a wide range of hotels ranging from youth hostels to stylish boutique guesthouses and top-end chains like Sheraton and St Regis. Outside of the main cities you'll likely find simple Chinese-style hotels, while out in remote areas you may find yourself in dormitory-style truck stops lacking running water or indoor toilets. In general standards are perfectly acceptable if somewhat uninspiring. A sleeping bag can be useful if you are heading off the beaten track.
Camping
If you are headed out to the far west or east, or even to popular destinations like Namtso lake or the Everest region (and certainly if you are trekking) it's useful to bring a tent and sleeping bag. You'll need to be prepared for potentially extreme conditions and cold but those properly equipped will find camping by a pristine turquoise lake one of Tibet's great joys.
Other accomodation
Budget: Popular destinations such as Lhasa and Shigatse have hostels or budget hotels that are well used to putting up foreign and Chinese backpackers. Lhasa's youth hostels are particularly popular with Chinese backpackers. Both dormitories and private rooms are generally available and facilities often include bicycle hire, internet access and laundry.
Unique accommodation: Lhasa in particular has some lovely boutique accommodation converted from historic mansions or even former monastic residences. You may have to forego some mod cons but charm, traditional architecture and even private meditation rooms or chapels more than compensate. Depending on the political situation it may be possible to overnight at a rural monastery