Hi L.,
I am a mom of twin boys... now 6 yrs old.
I believe you will find that having both...if not right away - eventually will be valuable.
In the beginning-- I would start out w/ a Tandom Stroller. Get one you can hook the car seats into so that you can be mobile without waking sleeping babies. We used the Graco tandom w/ car seats. There may be others out there now, but this did well for us. It is not the easiest to push around as compared to a jog stroller, but it works best when out shopping ( going through isles). You can place objects underneath if you need to go the grocery store for a few items with babies in tow.
Then... as they get a little older, you will be know what kind of side by side stroller will suite you best. They are lighter and easier to get in and out of the car.... but they have limitations too....
Hope this helps!
J. - mom to Stephen and Matthew