Rattan and bamboo are great for if you want to feel like you are on the beach. You can pick up rattan mats for super cheap. Then, cut them to size and glue them on top or inside furniture for a unique look. A weathered look is also very beach like, and would be a good treatment for existing furniture.
Another cheap decorating idea is to take palm leaves and hot glue gun them to lampshades (so that the throngs travel down to the end of the shade).
I would also suggest bringing in a light blue with the tan, as well as some greens. Fake birds of paradise would accent the design quite nicely. I'd suggest very light white curtains with rattan shades (again, very inexpensive).
This is another fun thing you can do if you have a large empty wall. Take a large, high quality scenery picture of a beach scape, blow it up until its something like 30 inches by 24 inches, maybe as large as 60 by 48 inches. Print it out 5x8 at a time on high quality photo printer. Cut the white, and frame them in nice frames. Hang them on your wall in order, and it will almost be as though you are looking out a window at the ocean. I will illustrate this later if you want.
If you get really into it, you can buy sand like wall texturing tools now. You can use that on furniture, or the bottom half of a wall if you want with a light blue on top. That’ll really make it seem like you walked out on a beach!
Oh wow, I so want to do this now! I'll have to ask my mom if she will allow me go wild somewhere.