Finding a double stroller proved to be a much more involved task than I would have ever thought. I am due in June with #2 and have a 2 year-old. I've been researching them for months. Everyone has slightly different priorities, so I would strongly suggest looking at reviews online for any stroller that you are considering. There is no better way to learn than from other moms already using the same stroller.
That being said, my main priorities were side-by-side design, great sun shade, good basket storage, strong weight balance (a stroller that could safely hold an infant and a large toddler - make sure to check that, several popular strollers only hold up to 35 lbs on each side, really made more for equal weight balance, in other words, twins), narrow enough to fit through standard doors, and not terribly heavy to lift when folded up. I didn't want to spend $700 or $800, and had a really hard time finding what I wanted.
Ultimately we lucked out with the REI big annual sale, and bought the Bob double jogging stroller for under $500. So I'd say to take your time and wait to find the right one for you. Good luck!