Luxembourg: for an overnight stay, Remich is nice if you don't want to stay in Luxembourg City.

Wineries:
Very good Riesling at Maximin Grünhaus (www.vonschubert.com). Some of their vinyards have been cultivated since Roman times. And Bischöfliche Weingüter Trier (www.bischoeflicheweingueter.de) for the sheer feeling of history when visiting their caves in Trier.

In Luxembourg, Bernard Massard (www.bernard-massard.lu/en/) do some decent sparkling, and their caves in Grevenmacher are open for visitors.