Willow - the seating in a voyager is 3 across the very back and 2 singles in the middle row - you can walk from front to back if you like! I have the babies seat in the midde row passenger side, another behind the drivers door, then 2 in the back at each side...so much space and anchor points for them all!
If you do look at grand voyagers look for a lx or limited one though - they are a bit longer I believe with a bit more boot space...