I would not take an 88 year old on vacation unless the location was an easy drive and the accommodations were elderly friendly- no stairs, grab bars in the shower, no area rugs to trip on, easy meals, great transportation, etc.
You can not expect an 88 year old to walk far, stand in lines, walk on a sand beach, endure long car or plane rides. An adult cruise where you can put them in a wheelchair and help them around the ship - keeping them out of strong sun and temperature extremes.