If you have only 4 hours between flights - you will be a bit tight - but if you go straight to the skytrain - go into downtown and stop at the Pourhouse on Water street. Sit at the bar - the bar snacks are great and this is a classic cocktail house. They will be friendly. There are some other options.

If you want some more info - i.e. - which day of the week will it be - send me a private message and I can give you come contacts and ideas. There will be little happening after midnight as most places will not have a license to serve alcohol beyond that time.