With two children, maybe you could get them to sleep in the one bed whilst away, or keep one child in with you, so that you dont' have to book as many beds. After all, it's a travel holiday - it doesn't have to be the same arrangement as at home, does it?
Our boys share a double bed at home so we try to book rooms with 2 double beds or 1 double and a fold out.
I think one of the great things about co-sleeping is that it simplifies traveling - there's no need to request cots and worry that bubs won't sleep in a strange bed because next to you it doesn't seem so strange.
Expedia is great for booking for families because it gives an option for how many adults and how many children whereas wotif and others just ask how many adults.