The first day I would build
Give the city one clear route before adding extras.
- Start with Fort Jesus and Old Town while energy is high.
- Use Nyali Beach as the natural reset instead of crossing town too early.
the easier plan is Fort Jesus and Old Town first, beach base or Diani route separately. That keeps the day readable instead of turning every good name into a separate detour.
I would rather leave one place for tomorrow than drag a tired route through Diani Beach just because it looked close on a map.