We get billing address, physical address, name and alternate name if needed for whatever, email if they want emailed invoicing, all the phone #s they want to give us. Once on the job we, or at least I try to get, GPS location and POCO meter # for rural customers. The POCO needs the meter # to verify location of service we are working on. One customer may have 100. One for each pivot, well, or grain system. If you are in business long enough you learn the names of first & subsequent spouses, children and occasionally grandchildren. Some of those children may give you hugs and want picked up just because you are there. (Limited to when parent is in room during BS time) I do not keep track of birth or anniversary dates.
On the other side of the desk, AD sent me a Happy Birthday wish the first of this month. How they knew, I have no idea. I don't think I gave them the info, but maybe so. None of my other suppliers wished me a happy birthday and I have known some of them for close to 40 years.