I reall like the current colors and your red roof. I think you can change the house colors and not change the fence color. Here is one example that is in a tan family: With a white trim and dark brown shutters, I think it would work. Here is another example of a tan shade: I also like this light grey with white trim: Would you consider a green base: Then chose either a brown or red for the shutter.

As the appearance of the garden has a modernist style with the straight lines and concrete furniture how about a Mondrian influence and add a bold strip of blue? It is a pond and with the right shade it could look really relaxed and contemporary. My daughter's suggestion is a chalky lilac!

I like @kelly's idea of picking a lovely fresh color of paint for the door. You can then bring it down onto the stair risers. Either a solid color to match the front door, or go wild and add some decorative elements to the risers with stencils. Or think of staining the door a great color and coordinate the stair railings and risers. I have an idea book put together for just such project that might spark some ideas for you. http://www.houzz.com/ideabooks/16700983/thumbs/Kathryn-Delany-s-Decorative-Stair-Risers

Teal? Just a thought sometimes I think it's smart to match or atleast go with the curtains you'd see in the window