My advice would be The Graco Duo Glide LX.
When we where expecting our second child we test drove alot of strollers, put a car seat in the back and drove the strollers all over the stores during Christmas time when the isles are extra crowded with our son in the front. We got some weird looks or people who asked to see the baby in the back.
Try out the regular model, I just didn't think it steered as well. A huge differance. Most of the other models where oversized and did not have a good turning radius.
I use my Graco double stroller all the time. I love it.
Also just a bit of advice. I know they are kinda spendy to buy new $150- $200 new. Normally you can find them on your local craigslist for at least half. I have seen them between $30-$90 normally. Hope that helps.