Right now we're contemplating a side-by-side jogger for outside (Kandace is a runner), a front-back dual for shopping trips (can fit in the aisles), and two of the "umbrellas" for when we're both together with the kiddos.
You don't need all those. Trust me, once you've used a jogging stoller, you won't ever want to use anything else. Joggers have nice big wheels and they're easy to push anywhere, any time. You can maneuver one with a single finger. You won't want to use a small stroller with plastic wheels after using a jogger. And umbrellas are the
worst - they have tiny wheels, they tip easily, the handles are low... also you won't ever want to push two strollers, even when together. The more free hands the better, trust me on this.
I'll give you my advice below, but I would get a cheap carseat stroller to use for a few months when they're newborns, and then look at side-by-side joggers and front-back joggers and decide which you prefer for permanent use.
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We've basically had twins twice - our first two were 11 months apart, and then our actual twins were born last November. So we've been through two rounds of needing a double-stroller.
We have used a Phil & Teds Explorer for our first two and it's by far our favorite stroller ever. It's both thin and short, so it fits through doors and down aisles easily, but also doesn't take up a long footprint. It's relatively lightweight. The only drawback is it's not great for newborns and can only accommodate one carseat. It worked for our situation cause the 1yr old sat in the rear and we put the newborn in the carseat adapter on top. But once they were out of the have-to-be-in-a-carseat size (which is only a few months) it's the best stroller ever. This will work for when you're jogging, shopping, and just going out. It's literally the perfect stroller for everything but two newborns.
We have a side-by-side that we like, but not as much as the Phil & Teds. However we have to use it because when the twins came, we also had a 15-month old (now 2), so we bought a Valco Twin Tri-Mode with a Joey seat to fit them all. Of all the side-by-side stroller we looked it, it was one of the best because it's thin enough to fit through any ADA-compliant door. The only drawback is that it's heavy and takes up a bigger footprint than the Phil & Teds. It was also too heavy for my wife to lift when the babies were born (she's 100lbs soaking wet, and had been on bedrest for several months so her strength was gone). She can lift it now, but it's still quite heavy compared to the Phil & Ted, which is lighter and smaller, and easier to set-up and take-down, and fits in smaller spaces both opened and closed. If we didn't have the 2yr old and need the third jumpseat, we would only ever use the Phil & Ted now.
What we ended up using for the first couple months with the twins was one of these:
http://www.target.com/p/baby-trend-universal-double-snap-n-go-infant-car-seat-carrier/-/A-14237532?ref=tgt_adv_XSG10001&AFID=google_pla_df&LNM=14237532&CPNG=Baby&kpid=14237532&LID=9pgs&ci_src=17588969&ci_sku=14237532&kpid=14237532&gclid=CL7jyOv_6L8CFc1_MgodcGwAiQ
It was perfect, lightweight, and cheap while the babies were tiny. Honestly, with twins you're not going to want to move them in and out of the carseats while they're tiny, so being able to pop the carseats into this thing was great, and it's super-lightweight, and super-simple, which is important for an exhausted, sleep-deprived new mother of twins.
I would highly recommend a cheap carseat stroller for the first few months, then once the babies are holding their heads up, switch to the Phil & Teds, which really will work for
everything from then until the kids outgrow a stroller completely.
EDIT: One other thing to mention. With every stroller you look at, have your wife take it down, set it up, and lift it as high as it needs to be lifted to get into your car. Every stroller is different, and the east of use, as well as the weight and ease of fitting it into your car will make a
huge difference to a mom who has to buckle two babies into two carseats which will be on opposite sides of the car, then run back around and take down a stroller and stow it while in a busy parking lot in the rain in the dark.