A slight variation on the OR78/US95 from Burns, is OR205 south from Burns. This passes Malheur Wildlife Refuge (birds around a large shallow lake), Frenchglen (a state owned inn), Page Springs Campground (BLM, popular with birders), possible side trip up Steens Mtns (w/o RV), Fields (remote gas station and malt shop), and NV140 to US95. It's more scenic than the OR78 route, but not as fast and straight.
In fact if you are up for some straight flat gravel you could take Fields Denio Rd for OR78 to Fields, along the east side of Steens Mtn and the west side of the Alvord salt flats (used for land sailing).
There are some hot springs in the area, including a rustic one near the salt flats, and commercial one with camping near Crane (on 78).
There are also some lava fields off of 78 south of Malheur Lake (and a round barn).
