Great space!!!

-Before you do anything I suggest giving the deck a coat of stain/sealant. It looks like it's about due for a coat and easier to do it now then when you have all your furniture and plants setup. Go with rich, deep tone to coordinate with the tan.

-Instead of focusing on small pots of annual flowers, I'd love to see you go with some big pieces that will stay outside all year, look great and create privacy. Think along the lines of the structural landscape elements you'd see in a yard....trees, shrubs...evergreens....just plant them in large planters instead. Each year you can add little pops of color with some annual baskets or perennials.

Here's some ideas.....