A.D.
I bought two double strollers. One is the sit and stand with the second seat. It is a good stroller that can handle an active kid standing and it has the car seat adapter. The reason I don't like this stroller is once my daughter was out of her car seat and sitting in the stroller seat she looked very uncomfortable. The seat has almost no padding and very ridged. She never went to sleep in that stroller.
The second stroller I bought I love. I bought the circo side by side. Chicco Trevi Twin Stroller - Extreme. Both sides lay almost flat maybe 15% incline, Folds very small (it collapses like an umbrella stroller) and my three year old son jumps in and out as he wants to. Also it fits though most doors with the kids in it.
With having both a front and back stroller and a side-by-side I would recomend the side-by-side.