From Gondar I took a completely packed minibus in the direction of Metema at the Sudanese border. This route is very scenic, with a pretty dramatic descent about half-way the road. 25 KM before the border, the small town of Gendewuha provides some basic lodging, with the Zenbaba hotel being the pick. This 4-storey building has a lively courtyard and rooms with cold shower (but no toilet) for 150 Ethiopian Birr.
The border at Metema is lively, but it is not recommended to stay in the town, as only very basic accommodation is available.
After traveling in North-West Amhara, I made my way to Benishangul-Gumuz Region (via Bahir Dar, Injibara and Chagni).
The first night I slept in Gilgil Beles, a surprisingly well-catered town just across the regional border with Amhara, down from the highlands of Chagni. There are several decent hotels here, including Tinsay Hotel, but personally I had a fine stay at the West Start Hotel for 350 Ethiopian Birr.
From Gilgil Beles, there is a direct bus to Assosa, leaving at around 6 AM in the morning. It follows the rough road to Guba, but turns south just about 10 km before reaching Guba town. From there, it is about 50 km to the bridge crossing the Nile, after which the road continues south-west for another 120 km towards Mengie and eventually Assosa, passing the town of Mengie. Almost the entire trip, which lasts about 12 hours, takes place on a rough road at low altitude, except for the last asphalted stretch of 25 km towards Asossa. Here the road rises steadily again towards about 1500 meters, which gives Asossa a more common Ethiopian mid-altitude town feel.