J.D.
we have the sit and stand and I LOVE it! My girls are 15 months apart, and I have been using it since they were maybe 8 months and close to 2 years... and are still using it to this day. The girls are now 3.5 and 4.5 years old. I would think a double stroller, especially since you ahve a 3 year old, wouldn't last that long. I can't imagine putting my 4 year old in a regular stroller seat. But that could just be me! I got ours at Target for about $120.