The park sees over 800,000 visitors per year, so if it is solitude you're looking for don't expect it here.  (Although there are some areas to escape into.)

The hatchery is worth stopping to take a look at.  Lots of holding or breeding "tanks" hold thousands of fish until it is their time to be released into the river.  Click here for a shot of the hatchery with fish popping up.  Don't forget to take a quarter to buy a handful of fish food and watch the fish attack a pellet like it was the last one they'd ever see!  =)