I was the same way: I walked past this place a thousand times and never once thought they were anything other than a banquet space. But they are open for dinner through the week (like Tuesday to Thursday and Sunday, I think--something funky) and the food is really, really good. The space is really gorgeous, too--like a 20's ballroom feel--and it was mostly empty (and so quiet). The wine list is a steal--less than 100% markup on most of the bottles, if my math is right--and the menu prices are damn reasonable ($19 halibut, for example).
All around solid place for weeknight dinner. Try it and let me know what you think. And tell me where you got that coupon.