we went for a week ( sun - sun) . both sundays were travel days. so had 6 full days. We did 3 days at DLR. 3 days are good. you can do one at DL one at DCA and the 3rd day for doing anything you missed. But if you can do 5 days, i would suggest that. then your not as rushed to get from ride to ride, as you have more time.
if you are also interested in doing other attractions, i would suggest going to Costco Canada.ca and checking out the Southern california citypass. it comes with 3 day Disneyland resort parkhoppers, 1 day seaworld and 1 day legoland . (when we went they citypass had universal instead of legoland) When you get to Disneyland, you can upgrade the 3day pass to a 4 or 5 day pass.
So we did 3 days disneyland resort, 1 day seaworld, 1 day universal. and we also did knotts berry farm. there is so much todo in southern california.
if you are also interested in doing other attractions, i would suggest going to Costco Canada.ca and checking out the Southern california citypass. it comes with 3 day Disneyland resort parkhoppers, 1 day seaworld and 1 day legoland . (when we went they citypass had universal instead of legoland) When you get to Disneyland, you can upgrade the 3day pass to a 4 or 5 day pass.
So we did 3 days disneyland resort, 1 day seaworld, 1 day universal. and we also did knotts berry farm. there is so much todo in southern california.
We do all of it at a very relaxed pace
. We treat DL as a Resort, not a quick one afternoon amusement park. We do our best to do everything and see everything at a relaxed pace and take lots of photographs. This includes the pools, waterslides, hot-tubs, cafes, and character meets in the DLH and the Grand.
, it was F U N ! Hey, we watch the Parades from a different place every time we see one! We even go to the back of the gift shop in the very back of Critter Country at least once every trip for some fresh FUDGE that is made while you watch! It is amazing how quickly five or seven days will go by when you are taking your time and doing everything 
. But even if I didn't go as often, I would still burn out with more than 4 or 5 days at a time.