We have a Trunki for DS (4) and he loves it. It's carry-on size, I suppose it would fit 10 days worth of clothes in his size, if they were summer clothes. However, it doesn't hold nearly as much as a proper full-size carry-on bag, and it's a bit fiddly to open (it opens split in half, so you often have spillage of items).
Pro: he loves to sit and be pulled on it, and to scoot himself around. He does love his Trunki.
Con: not terribly efficient, and if you have several children, they'll all want pulling around on them at the same time.
So if you're being very practical, I'd suggest getting proper suitcases. I have no suggestions as to which ones, though, sorry!