we only have two kids and got a t5!
we got the t5 'cos we thought once we're into an MPV we might as well have something we actually want. we went for the kombi, for a number of reasons, more security, easier to clean out, cheaper tax.
shuttles are cheaper to buy, better spec'd but more to tax.
as has been mentioned above, similiar length to many normal estates passat, mondeo, actaully shorter then an e class but wider... and therefore percect for 3 abreast car seats!
my (very slight and non typical van driver) missus drives ours full time (boo! i want too!) and after initial nervousness absolutely loves it.
it has gone from a luxury "if times get hard we can flog it" to a well loved part of what we do, cracking for extending camping holidays, day van, moving houses, bike transport.
there are a number of options for seating. we went for captains chairs up front for comfort and passing stuff to the kids. there are also 3 classes t28 / t30 /t32, this refers to load weight, bear in mind t32 require a class 7 MOT which requires a specialist centre and costs more.
engines wise we went for a 2.5tdi 130 bhp which i think is plenty fast enough and leggy enough for long journeys, also available is a 174bhp 2.5 and 1.9tdi 84 and 104 brake engine which personally i found a bit wheezy but plenty of people chip them up and are happy with them. i wanted a bit of grunt and the 130 has the potential to chip up to about 160bhp.
all in all we have no regrets, absolutely the opposite in fact and have many plans to pimp the ride from swivel chairs and sun canopies to phat rims and tints (innit)! sorry have gone on long enough, i'll let you get back to the nappies!
CONGRATULATIONS!