Over the short break, we went to Beitou as that's another area famous for the hot springs. The spring city resort usually has deals on here and it is very family-friendly.
We took the red line on the MRT to get to Beitou station. There's a shuttle that comes so be sure to turn right at the exit and then see the area I've circled for waiting for the shuttle.
Once there you can exchange the receipt you get from kkday to an actual voucher. The family pool is up on the 2nd floor I believe, there's an elevator that goes there and then you have to go through a long corridor hallway to get to the outdoors pool area.
Once you take your voucher to the ticket windows near the hot spring pools they'll have to go back to the respective changing rooms to change into your swimsuits and swim cap. They do provide a shower cap that you can use if you have forgotten swim caps like we did and towels and sandals.
It was very relaxing in the morning when there weren't too many people there but it got more crowded in the afternoon.
There are about 7 hot pools and 2 or 3 cold pools for soaking.
It was so relaxing that our daughter fell asleep right after a soak.