I) Larger Towns and Cities
Most larger towns and cities have affordable hotels, although not as cheap as you might imagine. Quality is generally consistent within the price range.
Basic hotels provide a bed and a fan with shared bathroom/toilet facilities. There may be more than one bed in the room but you are usually expected to pay for the whole room. The bigger the group of travellers, the more economical these rooms are, as more beds are often put in a room within reason to accommodate everybody without the price being changed. Some hotels have cheaper beds outside in the open as in smaller towns and cities. These hotels are not very clean but are cheap and perfectly acceptable for short stays.
Lower mid-range hotels - more likely to be found in Khartoum - offer the worst value for money. They may have en suite bathrooms, mostly evaporative air conditioning and satellite television, but for what you're paying two or three times that of basic hotels depending on your bargaining skills the rooms are extremely tatty and hotel owners will almost always subscribe to the philosophy of: 'Only fix something if the guest complains'. There will sometimes be rooms minus the bathroom/air conditioning/television for prices a little above those in basic hotels.
Upper mid-range hotels are the next step up, with spotless rooms of a far higher quality but prices usually quoted in dollars closer to what you'd expect in the West. You'll have little to find fault with, though.
Top-end hotels are commonly of the Five Star variety, and include the Hilton. The few are found mostly in Khartoum. They are much more expensive than the upper mid-range hotels.
II) Outside Larger Towns and Cities
Outside larger towns and cities hotels don't normally go above basic. That means bedframes with either simply a string mesh or with thin mattresses; that is not to say they are uncomfortable. They are offered generally in fours or fives in rooms where there is often a ceiling fan to keep things cool. The beds are usually cheaper - and more fun to sleep in - out in the courtyard under the stars, although there is obviously less privacy and security. As with the basic hotels in larger towns and cities, it is more often than not impossible to rent one bed in a room as you might in a dormitory. Hotel owners insist that you rent the whole room. Rooms become unavailable quickly at certain times weekends, for example. Showers may be bucket showers, with water straight out of the Nile if your route follows that river.
Camping in the wild is easy in rural areas outside the south as long as the usual precautions are taken.