Debbie - two additional items for you. Background first: We just purchased this. We have 2 girls 4 years apart. We realized when the baby was 7 months that we needed some kind of double stroller. We bought the Joovy you mentioned. I wish we would have had it when the baby was a newborn. We never used the car seat attachment, our baby was out of the infant carrier at 6 months due to weight and length.
I love the stroller and the girls are happy with it. My 2 additional items are this. I drive a prius, and it's a tight squeeze to get the stroller into the back hatch - it fits, but only in one direction,and I have to kind of twist it in.
The 2nd item is we have big kids. The baby is now 9 months old - at her 6 month checkup she was 22 lbs and 28 inches. There isn't much room to get the baby in and out between the tray holder and the seat. And the straps are already out to their full length, and I'm not sure how they will work when she has a winter coat on - we'll find out soon enough.
Love the stroller - no stroller is perfect!