That's an excellent idea.
If you are a WDW visitor, you can do Disneyland/DCA in two days. Longer is preferred for more relaxation, but if you know what you are doing you can see all the major stuff. Some rides are obviously skippable (Dumbo style rides, Muppets, as they are identical to Orlando), which helps - just don't make the mistake of skipping the dark rides because they are all worth doing to see the differences. Even if you only have one full day, you can still hit most of the majors - the CA parks are open much later in general than ours.
BTW, if $ is an issue, there is a Motel 6 within walking distance (they also have a shuttle along with the other local hotels - I think it's like $5/person/day for unlimited) that costs about $50/night. Sure, it's a Motel 6 - but the staff is awesome, and it's newly refurbished and very clean.