Originally Posted by ESpen36

You cannot take the bus airside from T8 to T5 unless you have a boarding pass (or confirmed itinerary) for a same-day flight departing from T5. You would need to arrive T8, leave security and take the AirTrain to T5 to visit the TWA Hotel, then return to T8 and re-clear security. It's pretty tight with just 2.5 hours in between flights, given that you will need to allow 5-7 minutes for each AirTrain ride, and there's no telling how long security lines will be to re-enter and get to your departing gate on time. It would have to be a very quick drink! (I personally would not risk it.)