Depends on where you're coming from, what you want to do, what else is running, blah, blah, blah...
So, at 50 cfs you can throw flat spins both ways and do all your flatwater tricks at the Library hole (it's really directly behind the police station). Nothing else is worth gearing up for, even if you live across the street.
At 100 cfs you can throw low-angle ends at the Library hole, and maybe the Bleacher hole, but that's rough on the boat.
At 150 cfs all the above apply and you can side surf at Grandstand (yippee!
At 200 Library is getting entertaining, so is Bleacher. There is also some greenwave front surfing at the top of the park. Grandpa's gets almost decent for left spins.
300 cfs and above the park is fun with plenty of play and worth your time.
So, even though I've been pretty ho-hum about lower flows, that does not prevent me from staying wet there. You can always do something at Library; I've surfed it as low as 30ish cfs. If you're already in town you might as well take a look for youself and maybe give it a shot...it's not like you're paying an admission fee!