I bought the Baby Jogger City Select last year with the intention of using it for DD only but convert it into a double if I will ever need to. And once DD thinks she's too big for the stroller, I could convert it back to the single and use it with LO only. Unfortunately, you cannot do that with a fixed double stroller i.e. side by side. My sister has a double side by side stroller and I always saw her struggling to get in and out of old elevators, or when putting it in her car. So when I saw the City Select, I thought it was perfect as I am not stuck with a double all the time! I never used the stroller in the snow but heard great things about it never having any trouble with almost 80 lbs of two babies.
I only bought one seat at the time and I plan to wait until LO is here to decide if I should buy another seat as DD may not be interested in sitting in a stroller anymore by the time she's 3 1/2. Till then LO will be too small to sit in the seat anyways, so I intend to carry him/her in my heart2heart baby sling.
Overall, I have been very happy with the purchase and would absolutely recommend it to anyone wanting a double with the option of turning it into a single on a whim. The only down part of this stroller was that you have to pay extra for ALL the accessories including the front tray! Some other more expensive strollers come with those accessories so the prices end up becoming very close to eachother once you add up the extras.
Hope this helps....