There are some good sites with lots of suggestions - put Seaside gardens into Google and you'll get more ideas than there's room for here. You'll need some good tough shrubs for shelter from the wind. Also it will help if you put your location on your profile please!

When you say 'flowers', do you mean perennials, shrubs or just summer type bedding?

Osteospermum seem unaffected by sea air in devon.....
Hebe too