Hello Gem,
We were looking at the car a while ago when it first came out, like you we have two children under 5 and (probably also like you) occasionally need to carry additional passengers (which for us would probably be grandparents).
We felt that the two rear seats were only for children and as the Ford man said are for occasional use only as so much boot space is lost. Access to the rear seats isn't easy either...
Have you looked at the Ford Galaxy? For the extra space, I think it is much better value, I think because it is more of a traditional 7 seater and people want to feel like they're driving a car and not a mini bus it's cheaper.
My best friend has a S-Max titanium 2.5 TDCI - they drive to Holland a lot and they love it, I think the Galaxy would have been better for them, if she wants to carry her Phil and teds buggy she can't have both back seats up, but they really wanted the s-max. I have heard lots of positives about the s-max. We decided it just wasn't for us as we were more likely to carry adults not kids, but it is a lovely car.....
I august Dodge/Chrysler are releasing a new model called "Journey" we are waiting for this! It has lots of cubby holes like a Voyager for all their junk as my car looks like a skip most of the time

It's doors will open 90 degrees to access the back row and the middle row seats have a better way of folding to make that access easier.
Its not on the dodge.co.uk site yet but you can see it on the dodge.com site.