Anything to do during a KUL layover?

Hello. I have an upcoming trip and my round-trip tickets both have a layover in KUL via Malaysian Airlines. First one is from 17:00 to 22:00 (5 hours), and my return flight has a layover of 21:30 to 8:30 (11 hours) of the next day, on (17th to 18th).

Anyone knows if there's anything to do during those hours? I'm not sure if it'll be smart to leave the airport during the 11-hour layover considering it's an overnight layover. As for the 5-hour one, I'm planning to just stay in the airport. Do they have anything to check out, like in SIN? Or do they have anything like an airport pod or something where I can maybe wash up and take a nap?

Or if anyone else have the same layover time as mine, maybe we can grab something to eat or drink together lol I don't feel safe taking a nap alone in the airport.

Thank you!