Northern Laos' biggest town, Udomxai (sometimes referred to as Muang Xai) has developed into a major travel hub -- primarily due to its size and location rather than its charm -- it has about the same level of charm as a major bus station.
While the distances in northern Laos are not huge between towns, the roads are still, in some places, in quite bad condition. Heavily-laden buses sometimes make their journeys at a slow pace, especially in the wetter months. All roads lead to Udomxai, however, and the town has grown and flourished over the years as travellers have been forced to stay overnight before departing for their intended destinations.
(http://www.travelfish.org/location/laos/northern_laos/udomxai/udomxai)