I'm right now pitching one of my groups next do something roughly historical in the 17th century and early 18th century Spanish Caribbean pirate vein. But with somewhat more magic and miracles than you typically find in history books, more in line with how the magic and religion was at the time popularly thought to work.  I'd personally like to see it with no demihumans (Elves, Dwarves, Orcs), because I'm pretty human centric, but we'll see how that flys with the other folks around the table.

This isn't really inspired by the Pirates of the Caribbean movies, but yes sort of in that vien.  Especially the second one.  But I see extending the campaign up north too along the mainland coast out of the Caribbean Sea proper too.

The concept for the campaign itself is running as a privateer and/or pirate hunter.  Sort of a hired gun for the man but with their own agenda too.

If anyone here has any suggestions for what, and why, they see as absolute essential historical reading for the era that'd be great. I've got some gleaned together concepts in my head, but more would be great.  Also experiences you've had running campaigns like this. What games you used, how things went, what the focus of the campaign was (ship to ship fighting, strategic battling, more hand-to-hand, more land based, etc.)  Even experience with things like Pirates of the Spanish Main, which I very much doubt we'd use, is welcome.

I could say that if you want a great gaming sourcebook for this subject, GURPS Swashbucklers is top-notch.

RPGPundit

7th Sea is an interesting choice for this sort of thing. THe game was designed with pirates, high seas and swashbuckling all the way.  It is not historically accurate (it's set in an alternative 'earth like' europe) but it does have some subtle magics  and secret societies.  Ignore the metaploting and you have a setting that feels pretty darn good for this sort of thing.

As for the system: ten sided dice in pools, a la L5R (same company).

For d20, the Skull & Bones book by Green Ronin is pretty nifty. It deals with the Spanish Main era of the Caribbean.