Disnee Dad Says..............................Personally, I would rent a car. It will be cheaper in the long run. US is maybe 30/40 minutes north of DL, but if you go at rush hour it will take about 4 days!
KNott's is more like 15 minutes away.
I would plan three days for DL/DCA
I would plan one exausting day at US
I would plan one not quite an entire rushed day at Knott's
I would plan two days in San Diego, with a one night stay. It's 90 miles from Anaheim and can take anywhere from 90 minutes to a week to get there! Do the Wildlife Park, thats another 30/40 miles of driving as it's in the middle of nowhere, but it's fantastic. This is the part where you regain your strength! After Wildlife Park, try Balboa Park and Old Town. Next morning, you lounge by the pool or check out the Pacific Ocean, or head back to LA, and go to Long Beach for the Queen Mary, or to Santa Monica to see the crazy beach area, or back to the hotel to soak.