Depends on the child I guess.. my son is 3 in August and still has a nap, often in the pram so we definitely need a double, but if your 1st is going to be older (difficult to predict) then you may get away with a single plus buggy board, also you can put baby number 2 in a sling if the first really needs the pram. Also, a double buggy (even a phil and teds) can feel quite large when you're on the bus etc so if it is feasible then for your first it might be nice to have a smaller pram like the bee just to make things easier in terms of weight, size, entering shops etc..