Hello - we've had 7 strollers single & double now! My girls are 3 years apart so we had the same quandary. We initially purchased the Joovy Caboose b/c it held the baby seat. Plus: It was cheaper and 10 lbs lighter than the Graco. You can get the fancier Caboose that is supposedly really light. If you get the Caboose the parent organizer is expensive ($25) but well worth it. Minus: not a lot of easily accessible storage. also just a bench for the big kid, not good if they still want to nap (mine didn't so that flew OK w/me). That was great for the first year. However, we really haven't used it now. That's because generally I make my now 4 year old walk. I either take my MacLaren (super small & light) or my 1-baby "full feature" stroller is the Peg Perego Pliko (sp?) P3 which has a ledge that my older one can stand on if she's tired. That was a nice feature I didn't find out about until years after I had it!
We live "in-town" so we do a lot of walking to library, store, etc and so for that we got the Baby Trend double jogger. I can't express the amazing difference in how much easier that is to push than the Caboose, with the same 2 kids inside. I think it's the physics of disbersing the weight but I'm no scientist! However, if you're only getting one stroller this double jogger is incredibly cumbersome to try to load into our SUV trunk. We really do that only once or twice a year.