I recommend paint. You have new as well as old painted shingles. A paint will blend these two different areas. Plus, the salt and wind will affect a stain before paint, paint will last longer in your situation.
You will need to carefully scrape off all the loose paint and prime the entire house with a good oil based wood primer that is designed for sealing tannins. Cedar might bleed tannins and cause some staining. Make sure to seal all the edges really well. Brushing and rolling is a good idea, this will push the primer into the wood.