I just bought a Baby Jogger City Select double stroller and LOVE it! It is easy to use (assemble, collapse, etc.) and has the maneuverability like you would find in a jogging stroller with only one wheel in the the front. This stroller has only been on the market for about 6 months. I also love the fact that if you want it to function as a single it can...and it actually looks like it was meant to be a single (not bulky). It's worth looking at if you are not sold on what you have seen so far. I didn't want a side by side because of how hard it would be to move through shopping isles and I think this is the best of it's kind. It is a little spendy but isn't much more then the Phil & Ted's stroller.
Also, the City Mini is not a double stroller and cannot be made to function as one (your first responder suggested it). I used a City Mini when I only had the one child and loved it...which is also what made me buy the City Select.
I was also looking at the Phil & Ted's stroller and just wasn't comfortable with the fact that one of my children would be so low to the ground and in what seems a precarious position. I know it is a safe stroller and have heard from others who love it. I also don't think it is as easy to get the child who is on the bottom out of the stroller as it is with the City Select.
I went to Baby Grand to test both of these strollers out. The one in Hopkins has the space so you can drive it around the store. Also, the girl that works in the stroller section is really well informed on the options out there and how they function. I highly recommend at least looking at them there to help determine which one you want to buy.
Hope this helps!