[bigeasy1]

You could do absolutely nothing and just call it "PATINA"

I think a high quality two part urethane would do a good job.I restored an aluminum boat and painted it with Sunfire urethane.
For more than ten years I trailered that boat all over New England on crummy back roads,and bumped into several docks and bounced a lot of down rigger weights off the hull.
That paint held up incredibly well to lots of abuse.
After all those years it looked almost as good as the day it was painted.

It was a lot of work however,I stripped it all down to bare aluminum,sanded every surface,and had to apply a coat of vinyl etching primer,followed by a coat of sealer,then the finish coat.

I thought about doing the windshield frame on my Tsunami,but the thought of doing all that tedious work,sanding and prepping all those small areas and weatherstrip channels stopped me from doing it.
I ended up just cleaning it with some Woody Wax and some bronze wool.It's far from perfect and there is some pitting,but I'm so used to it that I don't notice it.I figure it's a fishing boat,not a show boat.
People still give me thumbs up even with the aged windshield frames.

Good luck, post up some pics when you finish.