how about furama? i think they have dim sum all the time, but i wouldn't swear to it, plus other chinese dishes. mei shung, also chinese, is also on broadway. and you have plenty of good thai restaurants at the same corner-thai pastry is ok; tank, for pho. both furama and mei shung are pretty old school, and will have plenty of tasty, if not unusual dishes for your guests.
http://www.furamachicago.com/html/general.htmlhttp://www.meishungchinese.com/