I tip housekeeping if my room is tidied in a timely manner. If I leave the room first thing in the morning, and I return at 4pm and the room isn't made up, the tip goes away. I put it right back in my pocket. I leave my room in very good condition...the beds are pretty much made, the vanity area is wiped down, towels are in the tub if I want replacement towels..so, it shouldn't be too hard to get my room taken care of before mid-afternoon.
I tip the DME driver 'if' he provides a better experience than just driving the bus...if he handles a bag for me, that would justify a tip. If he is entertaining and makes the ride a nicer experience, he gets tipped. But, if he asks for a tip in any fashion, then the tip money goes back in my pocket.
Valet services get a tip.
Bell Services, that brings bags to, or from, my room, get tipped at about $1-2 per bag.
Servers get tipped at about 20%...yes, even buffet servers. If I get less than good service, the tip goes down. Really terrific service and the tip goes up.
I tend to tip on the heavy sided. BUT...I refuse to tip just because it's 'expected'. The worker has to give me a reason to tip. I have had incredible service from Bell Services at BW in the past. They were given $3 per bag. On the other hand, if I call down for bags and it takes them a long time to get me my bags, the tip goes to perhaps $1 a bag or $3 for more than 3.