For #2 (my husband likes to number my sisters rather than use a name..) with my almost 3 yr old niece and another niece on the way, we send home lots of fun new clothes and books for the girls - some new, some made with love. Some particularly requested items were a twirly skirt which my DD made, and a scarf to match the one I had made my sister for Christmas (it's winter there at the moment).
#4 received an antique cocktail shaker that I stumbled upon while browsing Nostalgia one day :)
and #3 owns a restaurant so I thought a handmade apron would be something she would like
It has a pocket to hold a order pad and pen, some vintage buttons and trims, and some paris newsprint fabric to remind her of our trip :)
Doesn't even come close to getting on a plane and seeing them in person but at least they'll know I'm thinking of them!