I agree with space saver bags. We have also used gallon size ziplock bags, squeeze the air out, and works the same. By using those we tend to get all of our stuff into 1 sometimes 2 suitcases for a family of 4. (dh, dd5, ds3, and myself). That includes 1 outfit per child per day with some spares and a couple pants/sweatshirts for cooler times, and 1 outfit per day for my husband and I. Also includes 3 princess dresses for dd, and a pirate costume for ds. If we take 2 suitcases it usually includes breakfast foods.
If it is just the 3 of you, you should have no problem fitting everything into 1 bag. I'm not sure how many souvineers you are buying, but I would think you should be able to fit those into a carry-on duffle for the way home.