We pretty much did exactly the same as Sailman at the ME.
We did give a few bigger tips to our favorite employees the day before we left.
We never felt like we were required to tip. But we had such great service, we were happy to give a little extra. Its personal preference, so tip or not, its up to you.
Our butler clearly stated that he treats everyone the same regardless of getting a tip, and in his case, I believe him. Awesome guy.
But to answer your other question, the butler usually checks in on you here and there to make sure everything is going well. They often leave small edible gifts in your room. Ours saw me drinking wine with dinner one night and had wine put in the room for us everynight after that. I've heard that some will make reservations for you, but we didnt ask ours. Keep in mind the butlers are assigned 20-30 rooms, so they are not always available. But they generally leave you their direct phone number.
They set up your hot tub at night for you as well, if you request it.
Edited: 2:22 pm, March 28, 2013