K.,
I read all the other responses, and have read a lot of reviews of various reviews of double strollers online. I have two girls (now 2 1/2 and 1 1/2), but I have a different perspective on weight and ease of turning, etc. than a lot of other mothers, because I never started with a single stroller. I adopted my girls together at 5 mos and 1 1/2 yrs. So here is my advice. Go inexpensive. All the bells and whistles don't matter a whit once the older one starts to scream that she wants to walk, and when she is riding, she is kicking or pulling at her little brother or sister. It will happen sooner or later. Of course, since big sister was walking a few minutes ago, the baby, who is now out of the carrier, is in the front. Why not get the view if you are the only one riding, right? The more features you have, the heaver it is. The heavier it is, the harder to turn. Remember, the diaper bag, your stuff, the weight of the stroller, and the weight of two little girls makes for quite a load to push. I figured out one day at a fair, that my husband was pushing close to 80-85lbs across a field. My rambling point is that nothing moves easily at that weight, and moving two around will never be a easy as getting one where you want her with all her sundry paraphernalia.
Make sure you have a place to put your bag and a drink or two, and that you can get in and out of the basket in the bottom. We have the Graco Duo Glider - yes, the front canapy broke off, and Graco replaced it for free, because it was a design flaw. Soon enough you will be moving up to a Sit-N-Stand (someone else described one of those), and then back to the single (maybe) before giving it all up.
Whatever you decide on strollers, enjoys you daughter and new little one :o)
S.