I tend to tip after the first few drinks, and I will tip enough for the evening... As Fozziedoggie indicated, you usually will see prompt service with generous pours! Most of the time, I only tip in drinking lounges as this is where I persoanlly require more service.

Do what you feel comfortable with, ie many Europeans frown on tipping since they consider it part of the hotel charge. Americans tend to tip for everything, so its really up to you.

I firmly believe that people are motivated by money in a service environment, so I tip! In my opinion, it brings up the level of service in general. I travel to many of the same Executive lounges in Asia and Europe, and servers do remember.....