X.O.
When you go into the city, are you walking around in the downtown area? If so, I'd definitely go with a tandem stroller, or you risk getting angry fellow pedestrians downtown.
We have 3 double strollers: a side/side Combi umbrella, which is very lightweight and great (I think it was around $200); a double jogger made by Baby Trend, which was about $250 (it holds my Graco SnugRide infant carrier), and is much heavier; and a Graco DuoGlide tandem. Some women collect shoes--I collect baby gear ;-)
I have had the Graco the longest--it was about $150 when I bought it 4 years ago, and is the one I bring when I am going to the Mall, or to a museum. The others are simply too big. I use the others when we are at the zoo or park.