Definitely check out the Celebrity Millennium Class ships - their penthouse suits i believe may sleep six - they are huge. We generally take a Celebrity Suite because it has floor to ceiling windows and great viewing particularly for AK. However it only sleeps 3 so we take an inside cabin across the hall and it is a good deal, plus we get butler service, etc. and there is a nice living room to hang out. If you take the PS make sure you are ok with being in the back of the ship.