I always tip my butler, and concierge. And I tip my restaurant server and steward if I am very pleased with service. But I also always remember that butler and concierge are not working out of the goodness of their hearts, just hoping they'll bet enough tips to live on. From what I've read these are coveted positions and are paid a bigger salary than many others on the ship. If others would like the job it must be a good job! So I tip well, but it's because they've done a good job, not out of pity like for a beggar.