The Urban Detours are really nice, my childminder has one and it looks so snug and comfy, plus is skinnier width ways than my XTS twin twister.
I definately recommend a side by side, I found with the tandems the little ones don't have much room and aren't that comfy. I dug out my jane powertwin to use yesterday and it's horrid! Ella couldn't see a thing from the back, and Alex just look squashed in up front.
My XTS is much comfier, but so wide. It's a dream to push though.