hello fellow lunartick!
We also have and love our H621. It is most comfy and plenty of room for entertaining!
We have two offspring, one is 14 and the other 21. This year we managed to talk the eldest in to joining us for our holiday in the Alps and he brought a friend from university. They stayed in a 'pop-up' on our pitch.
The youngest, always sleeps in the dining area bed. We just pull-out the side bench (as you know) it easily makes up a single (or double with the table).
It rained, the whole time (sadly) so we had 5 damp campers in our lunar for the duration, but I can honestly say we didn't get overcrowded. They still slept in the tent but day time and evenings were very comfortable and cosy indeed.
As time goes by, we are getting more than the odd night away without the kids now. It feels like we are staying in a hotel! Well, almost....I've certainly stayed in many less comfortable ones anyway...and the views!!! Well that's what I love the most about camping, how you pop that blind up in the morning and see a different view every time. Oh JOY!
LOVING THE LUNAR!!!
By the way: Ours is 2005 and we have had it since 2007. Might consider something shorter in the future if the kids stop wanting to be with us, and if I'm honest, I preferred shorter vans to drive but we are very happy with the quality of fittings, space and comfort it provides. Particularly that we can go away for two weeks and not be glad to be home like we have done in the past with a small van and family.
All the best, will look out for you!