I think that by seeing lots of boats and there layout you get a really good idea of what will work for you.
An ex's boat was a trad so the layout was the best it could have been - stern,engine room,bedroom,bathroom, kitchen,saloon. It worked well for him.
When I looked at my boat I wanted a cruiser stern and reverse layout so its stern,kitchen , saloon, 2nd bedroom, bathrooom & bedroom. I love that when the boat is full I can still see and everyone whilst we cruise and when we stop the back becomes a "patio" with chairs and a table.
Good luck with your search.
Louise