Hi there, and a big welcome to FT

If your layover was of similar duration but during daylight, I would be advising (in fact instructing!!) you to get yourself into town, simply because IMO seeing as much as possible of this big world we live in, for as long as we are here, is ALWAYS better than hanging around for hour after hour after hour in a lounge (however luxurious).

But as eternaltransit had already noted, it's an overnighter, you will want some quality sleep, and so the advice already given is definitely your best option ^