OK, so we have been looking at camper vans on and off for a while. Would like a VW T4 (reliability, size is good etc). The problem is that (a) there are an awful lot more 2 berth than 4 berth vans out there, and (b) pop top / high tops both have their downsides. We used (many years ago) to have a T 2.5 that was just a regular van with a bed in it, and it was easy to drive / live with etc.
Realistically, the van is likely to be used a lot for days out at the beach (we live by the sea), overnight camping at the beach or after parties etc, some long weekends and really not that much if ever for longer trips away.
So, I'm wondering about the possibility of getting a 2 berth non-high top van, and improvising a bed for dd across the front seats (DH very good at such stuff - he put in the rock&roll bed plus cupboards in our previous van). Does this sound totally mad? DD is 9, so old enough to sleep in her own tent (and/or share tent with a friend) if she wants to at small field type campsites. Friends' 14 y/o sleeps across the front seats of their Merc van (but it is wider). But then they share the double bed in the back with their 2 other kids so have lower expectations I think than I do for amount of sleep to be gained 
The other possibility of course is to look for a non-converted van & put in some kind of conversion to our spec - at which point we can start thinking of semi-high tops which might be absolutely perfect in terms of a wee bit of extra headroom.
(Budget is probably up to about £12K max, which doesn't go that far with a non-ancient VW & DH is very determined not to have another van where we have to travel permanently with full toolkit at the ready!)