Well, having gone to both places, I would classify WDW as more of a destination in itself...the whole resort feel of the area, and frankly it's just sooo much bigger! DL is lots of fun, also, but as someone noted, it's within the city of Anaheim, with not a lot of room to grow into. I think they are working on another park (water park, I think?) on a close-by site for the future. We also notice that you feel much more immersed in the Disney vibe when at WDW--again, I think it's a function of the size of the place.
Once in the park, though, remember that there are some things that are *better* at DL than the Magic Kingdom...Pirates is a much better ride, there's Indiana Jones that WDW doesn't have, Peter Pan is better. The whole Fantasyland area is much more intimate (some would say smaller).
I would say that since you're on the east coast, that I would tie in a visit to DL with a trip that includes more of Southern California. You can go to San Diego, parts of LA, etc. I wouldn't say you could spend a week at DL itself, the way you could at WDW.
For us, coming from farther up the west coast, we see DL as a mini-trip. The trek out to Florida is for our longer vacations--10 days this time!!
But you know what? It's all Disney...therefore, it's all good.
