It all depends. I could go on a 3 week trip on my own carrying less than I do for an overnight business stay. I used to have a mania about packing light, carry-over from my serious hiking days. I still want to pack light if I'm going to be moving around a lot lugging my own stuff. But if I'm going by taxi and bus straight to a hotel and back-to-back meetings it really makes no difference at all (and impresses no-one) if I have one piece of luggage instead of two, and with two I have the space to pack running shoes, casual clothes so I don't have to wear the hoity toity ones ALL day, soft slippers ditto, a book or two to read, all the stuff that makes a trip just that more comfortable. And a lot of my business trips the most important thing I pack is tall rubber boots...