Those sit and stand strollers? We had one of those and they are great - easier to manuever than a real double stroller too (its amazing how many people will not even hold a door for a woman with 2 babies and a giant stroller).

We started out with one of the ones you were talking about - the car seat/carrier/ stroller jobs - those are pretty standard and really easy to use I think. Then we switched to straight double stroller, then went to the sit and stand one. My guys are just 1 year apart.