Hiya Dana!
Welcome to planDisney! Sometimes after a long day, relaxing at the pool does wonders on sore feet and legs and is sometimes my favorite part of the day. However, at this time, neither Disney's Art of Animation Resort nor Disney's BoardWalk Inn have pools that are open 24 hours a day.
Disney's Art of Animation Resort Pool hours are 10 am to 11 pm for all the pools including the leisure pools which are the Cozy Cone Pool and the Flippin' Fins Pool.
Disney's BoardWalk Inn's pools which are the Inn Pool, Inn Pool Spa, Villas Pool, and Villas Pool Spa are open from 7 am to 11 pm. The Luna Park Pool, Luna Park Pool Spas, and the Luna Park Kiddle Pool are open from 10 am to 11 pm. The spas are what they call the hot tubs.
They are open pretty late but know that hours can change at any time due to weather or other variable conditions. Always check the pool hours when you arrive to confirm and don't forget to check the Recreation Guide posted at the pool area that showcases all of the fun events that Cast Members will host by the pool or on the grounds. My family's favorite is when they organize marshmallow roastings which are delicious and free!
I hope this helps and that you have a fabulous time enjoying whichever Resort you choose.
Happy Planning!
-Nimmy