If you can make it over to BWI, UA is matching Southwest's $198RT fares to Oakland. You could easily do something like BWI-ORD-DEN-OAK and make that work for you. Fares are not being matched out of Dulles or National. You have to travel on T/W/Sat to make that work.

I looked at a second $198 fare on this route that looked valid Mon noon-Thurs noon and Sat. You may have to play with dates to make it work.

You could probably make it work to other destinations too, such as Las Vegas or the LA area. As others have pointed out on a different thread, Las Vegas normally does not usually requite a Sat night stay. UA has a $198 fare for T/W/Sat, and $218 fare for other days. That might be your best option, using the ORD/DEN connections.

Tom