Cranking up minimum power to 20 dBm is not a best practice; it should be capped at about 18 dBm maximum, since that is the maximum that many mobile client devices can transmit at. For a while, Ekahau recommended min 14 / max 17, but I think they've more recently lowered their recommended min to 12 or so.
Here's a great video that explains why NOT to line up access points down the hallway. Long story short, they should be installed in the rooms. They even include a hotel example (starting at 6:38) that shows how fewer APs can be installed to achieve adequate signal throughout if they're in the rooms than if they're in the hallways.
https://www.youtube.com/watch?v=cYvP8Ck2zDY
A site survey and predictive redesign using a tool like Ekahau, Hamina, AirMagnet, etc. will be the best way to determine a path forward.
Disclaimer, I do not work with hotels specifically. But, I do work at a university where we have hotel-like suites. We use wall-mount hospitality APs, typically in every other room, staggered floor by floor. If your hotel has data jacks in the rooms, you might consider a hospitality-style deployment if rerunning wires for overhead APs in the rooms isn't feasible. Personally, I'd prefer if we could move away from hospitality APs and go with overhead models instead (like a 916x series) since the quality and stability of the hardware and software tends to be better on those. Plus, the signal is able to propagate to the clients better with the AP being line of sight rather than hidden behind furniture or in the walls like a hospitality AP might be.
