Grab bars at back and sides of shower, tub and toilet or wall reinforcement for later installation - ensure these are professionally installed because if it were to give way the fall would be severe. Bathrooms with turn around space for walker or wheelchair - this is an unlikely renovation but do so if you have the opportunity. Higher bathroom counters - bending over makes it difficult to keep balance and is harder on the back. Kitchen Kitchen cabinets with pullout shelves and lazy susans - it should be a law that lower cabinets have large drawers instead of fixed shelving. Easy to grasp cabinet hardware - C pulls instead of knobs are preferable.
Task lighting under counters - better lighting means fewer kitchen accidents.
Cooktop with front controls - this will help prevent clothing catching on fire. Side by side refrigerator - much better than the having to bend over for the vegetable drawer or consider a freezer on the bottom. Adjustable upper shelves and pull out lower shelves - fixed shelving cannot adapt to your changing needs. Lower kitchen counters - only if there is a problem with your height. Gas sensor by gas cooking, water heater and gas furnace - loss of smell can be a problem with aging and you may miss a real danger.