Non-flowering but colorful for shade? Wandering jew (tradescantia), or variegated philodendron (pothos). Spiderplants thrive anywhere. Coleus (some are trailing). None of these will drop flowers on the deck.

I can't give you advice about plants that do well near the shore but to elaborate on Yourpal's post, I find that houseplants do better on a shady porch than annuals and perennials. Garden plants I've tried in the past tend to do well on the outfacing side but do not stay full on the house side.
This year I have rabbit ferns that I wintered over from last year. They are pretty easy.

Thanks for the advice. I ended up getting Bridal Vail. I never used it before, but the nursery I went to suggested to try it. It kind of reminded me of a Wandering Jew with tiny little white flowers. It's pretty and will get very full.

I always thought it was a type of Wandering Jew. My mother had one in our livingroom growing up and it was a very easy plant. Pinch it back once in a while to keep it full and if it gets too long, don't be afraid to give it a haircut. My neighbor grew it on her porch and it did great.