Icpteck, 10% in the US will be met with horror and negative reactions! 15% is really the acceptable minimum to tip in a restaurant. For a taxi or doorman a couple of bucks is fine. For housekeeping, it is not required as they are on a different wage scale but it is always a kind gesture as they are hard working and on minimum wage. I would suggest however to place it in an envelope on the bed. For most of europe in my experience service is included but doesn’t always go to the staff so 10% would be fair. Others on here will be able to give more insight I am sure.