4 berth or spacious 2 berth ? The choice is yours. Most 4 berths allow flexibility at the front end to sleep two people if require. The rest of the time you can just class it as a 2 berth. You can't get fixed single or double beds in a 2 berth, so expand your horizons.
There are lots of different layouts available so do your homeowrk and come down to work out which suits you best.