When I had my second child I used the Sit N Stand double stroller. My older child could sit (fully buckled in) or stand when we'd go shopping. The front seat fits just about any baby carrier, but some people don't want the baby to be in the front. It was a little heavy, but easy to set up & take down. The only time I thought it was hard to push was out on the sidewalk since our sidewalks are slightly tilted.
I did a lot of mall shopping & liked the stroller for that since it was narrow & I could get through the clothing racks easily.
Make your decision based on where you plan to use it the most. Since I was a big mall shopper, a side by side wouldn't be good, but the Peg Perego Aria is great if you're outdoors often.
Good luck finding the stroller that's right for you!
Jan :)