We have the Mountain Buggy Duet and I'd highly recommend it. It's very narrow but comfy for my newborn (actually 4 months now!) and my very tall two year old (not a confident walker). It's very manoeuvrable and feels lightweight to push, even one handed. Still a pain in the a*** to get in the boot but actually not much bigger than my daughter's single pram. Makes it so much easier to get around and I use it with just my baby if my daughter is at nursery and just pile all the shopping in her seat! Xxx
I only use my double stroller for walks around or neighborhood but we go for long walks and the walks are essential for my physical and mental health. I take the single stroller when we go out around town. I have a Chicco (front & back seats) which has been fine. With any front back stroller, be mindful of your suspension or you are going to get squeaks, especially as your kids get heavier.
I would go double but side by side. I need one due to having a 13 month old and being pregnant with my 3rd and they will be 18 months apart roughly. But they are ridiculously expensive 😩