Hi,
I am not sure if you have bought your pram yet but I have a 24mth old and 7 mth old and we went through the same dilemma's. I found that the side by side ones were too wide to fit through most stores and some of the long ones were like pushing a shopping trolly. So we went with a relatively new brand of pram. It is the "Phil and Teds" brand. You have a normal 3 wheeled jogger with an attachment at the back underneath the main body of the pram for the add on. The shade is good and you take up no more room than a normal pram. If you would like I can email you a pic of the pram.
I have found it terrific, as a side note the company is great if there are any problems, I had an issue with the brake on one side and they had it fixed and back to me in about 4 days.
Well I hope this helps, let me know if you would like a pic.
Amanda, ACT, 24 & 7mths girls