I always just used a skateboard for the back of the pram when my first three were smaller and that worked cause none of them were bolters or anything like that. But anyway, I would go for the side by side one because they are a bit safer too - I've seen those jogger ones with the toddler seat tip over quite a bit. As for the space, I assume you're like me and do all the shopping etc when you have the least amount of kids with you? If you do you can always fold some of the seats away in the very back to give yourself more room for shopping. We only have our 3rd row of seats up when we are all going somewhere, otherwise we have no space left either. You could possibly still use the jogger if you go for a walk or something like that. I have a big steelcraft pram that I use outside a lot when I go for a walk or stuff like that because the wheels are bigger and much better for that than the stroller.