DCA is by far a "Full day park" if you use WDW's standards. The amount of attractions the park contains alone could allow you to spend a whole day there. Paradise Pier by itself has 9 attractions and 2 shows I believe. While everything may not appeal to everyone there is something there everybody will enjoy.
Disneyland dwarfs DCA in attractions but it still has a very respectable lineup
Buena Vista Street
WOC - Fantastic show
Pixar Parade
Soarin' over California - The original
Grizzly River Run - 100x better then Kali
Animation and Turtle Talk
Monsters Inc - Great unique dark ride
Aladdin - Great stage show
Tower of Terror
Bugs Land - for the little ones
RSR - far superior to TT
Luigi's - remake of flying saucers
Mater's - Great little ride
Little Mermaid
California Screamin' - better coaster then Rockin imo
TSMM - with far less wait
Mickey's Fun Wheel - (of Death)
Symphony Swings
Sky School
Golden Zephyr
I could go on and on and this isnt nearly everything in the park. If this isnt enough to make it a full day park then I dont know what is. By far the best part is if you want DL is a 30 second walk away so you can park hop as many times as you want if you ever get bored.