ekc,

First off, I LOVE renaissance faire-jacobite-pirate shirts with big poofy sleeves*.

Second, I advise the sweater. Everything has it's place and those Highlander (Jacobite) shirts would be too theatrical for a simple Christmas supper. It would make you appear to be wearing a costume instead of clothes.
Go with a sweater and maybe a nice tie (you never get a second chance to make a first impression).

Save your romantic finery for a highland games, a renaissance faire, scottish country dancing, or other times where it will be better appreciated.

Cheers


* I watched WAAAAAAAY too many swashbuckler movies as a child