Originally Posted by
djk7
Porters/Sky Caps expect tips for helping with luggage.
Bars/restaurants - tip the same as outside the airport.
Lounge bars - In lounges where drinks are free, but not self-serve, read this
thread. In a nutshell, some people do, others don't.
I'd probably also add drivers - such as rental car bus drivers if they help with luggage or hotel shuttle drivers dropping you at the airport or your hotel.
timboy219's post says they should be excluded, so this is a case where there is some grey area and its up to your discretion.