According to ideal-LIVING, the top 10 trends for the 50+ market include:

Open Floor Plan, Disappearing Formal Dining (we've heard this for years yet we continue to see them), Smaller Niche Spaces (such as a small built-in desk in kitchen or bonus room instead of having an entire room devoted to an office.  Don't most of us just sit on the couch with our laptops anyway....), Outdoor Living Spaces, Eat-In Kitchens (a large island with seating is a great way to take advantage of the space), Low-Maintenance (many planned communities offer this), Multi-generational, Three-car Garages, Snore and More Rooms, and Dual Master Suites.