Our kids are 22 months apart. We bought a used Graco Duo Glider for about $40 when we had the second baby. The infant carrier snaped right into it (it didn't match, but I didn't really care). We used that for about 6 months (until the baby could sit up well), then purchased a new Inglesina side-by-side, umbrella-style stroller (I think it's called a Swift, cost $179 at www.albeebaby.com, with free shipping). The Inglesina folds up incredibly small compared to the big Graco double, and it's narrower than the cheaper side-by-side doubles, so it fits nicely through a standard doorway. My husband likes the high handles (I think it was even the tallest stroller on the market when we bought it). We've cruised the neighborhood, the malls, etc. for 2 years in it, and still use it occasionally if we're going to be out long enough for my 4 yr old to get tired of walking. The seats have full recline, and recline independently, so even a small infant can ride in it. We didn't use it when the baby was tiny simply because it's soo much easier to transfer the infant carrier around.
When we first started looking at doubles, our favorite to "test drive" was the Peg Perego Aria Twin. It's super lightweight, but it's rather expensive. We couldn't find the Inglesina in stores -- we bought it based on online reviews.
We've been happy with the Swift. Only complaint is that the canopies are a pain. In 2 years they may have changed the design though. We just popped them off and left them in the garage :-). Also, the seats might be narrower than some. It has never been a problem for out skinny kiddos, but might be a complaint for kids who are built more stocky. Probably couldn't put a larger 4 yr old in it. Our 4 yr old just happens to be petite. I can't imagine my son still fitting comfortably when he's 4 :-)
I will say that considering the use we've had out of it, I wouldn't have felt bad about buying the more expensive stroller. I feel like we would have still gotten our money's worth.