Activities I can do before my transfer flight?

Hi everyone, I’m arriving at Bangkok Suvarnabhumi at 11:45pm actually off for a trip to Laos via Nakhon Phanom from Don Mueang from 11:40am. So basically 12 hours after.

I know airport to airport transfer will start at 6am but are there any shorter or realistic activities I can do before my transfer flight?

Thanks!

P.S. I’ll be returning to Bangkok a few days later.