What an excellent post, Afrodyte, and your ideas sound great. Unfortunately I am too short of time at the moment to help your playtesting - we have one baby already and another on the way!

Of the two scenarios you suggest, the first sounds like the best to me. Plenty of scope there for action with very little detailed narrative from JRRT to restrict ideas. The second might be a bit of a non-starter, I remember some sort of quote from Akallabeth (I think) about a horrible fate awaiting anyone who carries a quarrel to the Undying Lands - I think all the old greviances are meant to be buried, but maybe not.

One time period that really appeals to me is the mid to late second age, when the Numenoreans are forging their empire in southern Middle-Earth. Whole kingdoms are created and destroyed, and anyone can make their fortune or see it destroyed - just pack a ship with some warriors and head off into the unknown!

Good luck