Without a doubt I'd go to Grand Cru at Belvedere Square.
You can order off the menu at Grand Cru or enjoy something from one of the other places while sharing a bottle of wine at Grand Cru. I think the bottles are well priced and it has become my favorite place to unwind.
Great choice. Good cocktails, too. And whilst drinking you can eat anything that's sold at Bel Sq -- sushi, smoked things from Neopol, Atwaters soups, etc. -- not just the tasty bar snacks prepared at Grand Cru.