Now with baggage weight limits at 50lbs and most airlines charging for even the first checked bag you have to find the happy medium. Maximizing cargo space vs. staying below the 50lb limit (figuring returning with souvenirs) vs. keeping the number of bags to a minimum. My wife and I have 2 young boys and we are able to pack for all 4 of us in a larger rolling soft side and a large duffel bag. She is free to push the stroller and carry a backpack (carry-on) and I pull the rolling soft side with the duffel stacked on top. I've found the duffels that come in most luggage sets are not heavy-duty enough to stand up to carosels, airline bag throwers, etc so mine is of heavy canvas.