Is considering the length as (the most) important governing factor a mistake? Is the cost of a boat more related to the displacement. A longer / thinner boat may serve the other criteria as well and certainly sail better. It is only the need to pay marina fees that dictate short fat caravan-yacht.
My preferred layout:
Stern locker, 0 to 2ft.
Full waterproof bulkhead.
Cockpit, 4 to 5ft.
Entrance, 3 to 4ft - This is a key area when sailing, it is a transition between the dry interior and wet cockpit. In colder climates it is where you wish to be. Everything is to hand and the main cabin stays dry. Contains: Navigation & emergency equipment, Toilet, Hanging space for oilies, reclining seat for catnapping.
Full waterproof bulkhead.
Kitchen 3 to 4ft - a semi dry space. The kettle should be reachable from the entrance. Wood stove one side.
Half bulkhead, in emergency / storm could be infilled to above the waterline.
Sitting 6 to 7ft. Removable dining table, visitor bunks.
Full waterproof bulkhead.
Bedroom, 6 to 7ft.
Full waterproof bulkhead.
Locker 3 to 5ft. For lightweight objects - fenders, ropes. Anchor locker, if full chain, one bulkhead back.
O/A length 25 to 34ft Beam, say 6ft.
cheers Mark