If you want to avoid California and its roads, then go through Lakeview (97, 31, 395). You will still see a bit of California, but not too much. This route takes you to Reno, then go south through Fallon, Tonopah, etc. Eventually you will get to Las Vegas.
Another route would be to go East from Bend to Ontario (20), then through Boise (I84), to Salt Lake City (I15), Las Vegas (I15),.... This route would be freeway after the first 200 miles across the high desert between Bend and Ontario, and would be longer.
At Burns, OR, about 130 East of Bend on 20, you can go South into Nevada to Winnemucca. From Winnemucca you can go SW to Fallon (I80, 95), or go SE (I80, 305).
There are lots of routes. It all depends on your time schedule and adventurism. Most logical routes will go through Las Vegas, unless you want to get into the Rockies.