I have 4 batches of 3 gal port kits going, and 3 more on pre-order. I don't want that many 375ml bottles around. So I bottle 8 in 375ml bottles, and the rest in 1.5L bottles. When I get low, I will rebottle a 1.5L into 375ml bottles.
When I went on a cruise, I rebottled two 375ml into a 750ml bottle. The cruise line lets you bring 2 bottles (up to 750 ml each) onto the cruise. I brought that and a bottle of regular wine.