Yeah, we've traveled a couple dozen times with the one child, and had that one almost down to a science (there's no such thing as completely down to a science when it comes to traveling with kids). We're more trying to figure out the move up from 1 to 2 kids. We're taking the two carseats regardless - that's a non-negotiable. Checking the toddler and attaching the infant to one stroller or the other.
My question was specifically: double stroller or two single strollers?