tips for furniture delivery?

I'm not sure if you are supposed to, but I have this year because I appreciated how careful they were with the delivery. They showed up on time. They gave me some tips on how to use a specific piece of furniture. I rejected a piece of furniture, and there were no problems with the return. I gave $10/each to 2 guys.

Prior to them showing up at my door, I had one crappy furniture delivery to the same apartment. The guys were late, made me worry that they would drop the furniture, didn't wear white gloves even though the store (Jensen-Lewis) makes a big fuss about the fact that they have White Glove Delivery service. Whatever. No tip to those clowns.

Tip if you appreciate the service they provide. To me, given what I have spent on items I've had delivered in the past, the additional $10/person or $20/person for many pieces, makes little difference to me and means a lot to them. I feel timely, careful, neat, polite service deserves something. But there is no "rule." Do what you think is right.

Helpful, thanks.