Hi OP.
We have a 6 bed tourer and our DC are now 11 & 13 and doing everything they can not to come on holiday with us this year. However we have had 5 years of lovely caravan holidays with them.
We have a double bed that remains permanently up at the back with sheets on - when the kids were little they slept on bunks above, now they are older they have a blackout tent each in the giant awning. I DO NOT convert the front seats - that way madness lies. If someone wants to come in from the awning they have to sleep on the sofa with the dog!
We keep ours on a seasonal pitch all year round in Cornwall, we are allowed to leave it all year and never have to move pitch.
It is important to get 'fully serviced' so that you have your own constant water supply and grey water drain, meaning you can keep the hot water coming all the time without having to roll your water butt to collect and dispose of water. A holiday does not involve rolling a water butt.
We also have coffee machine/steamer, flat screen internet tv which we connect to our phone hotspot, some games etc. As we leave it there, we have a storage shed with the awning, wetsuits, body boards etc. at the back of the van.
We also have a thick feather matress topper for the main bed, as well as feather pillows and white cotton sheets. There is absolutely no need for standards to drop whilst sleeping in a field!
We 'pimped' our van, stripped out all the brown and beige, painted it white and grey, put faux oak flooring, stick on 'metro' tiles behind the sink and heatproof white paint around the whole kitchen. We had navy cushions covers made and put those star curtains in the ones that are a bit cath kidston'y.
And the most important point is - no poos in the chemical toilet.