I found a hidden gem pool package at the one and only hotel with an indoor pool in Bali.
Yes! This is the pool package at Marble 8 Restaurant at Dream of Aventus Hotel Kuta.
For 95,000 Rupiah, their food is worth it! The portions are generous, and you get a towel too.
However, I found the pool water to be cooler than most outdoor swimming pools, perhaps because it's not exposed to the sun (my assumption). So if you're bringing kids, maybe bring some eucalyptus oil for after swimming.