Bangkok - Best Italian Restaurant and Best Middle Eastern Restaurant
I definitely second tk467's recommendation, L'Opera has great food and very pleasant atmosphere. I can warmly recommend their rack of lamb, dover sole and the oysters.
If you prefer something more contemporary, try the Opera Riserva wine bar right next to it.
http://www.lopera-bangkok.com and http://www.operariserva.com
For Italian I like Delicatezza on Sukhumvit soi 55 (Thonglor). It's run by a Thai lady who lived in Italy for a long time. Here's a review:
For Middle Eastern I like a Lebanese place on Silom, near the BTS 'sala daeng' stop, on the same side of the street as soi 2. I think the name is 'Beiruit'. It's inside a plaza, I believe it has KFC & Oishi Shabu Shabu at the front. Walk in and it's on the left side. The owner is nice and his food is good.
Yep, Calderazzo is a good option, chef is Australian Italian so kind of a Med-Italian menu for want of a better description.
Italian food seems to have taken off in BKK so there's no shortage of options. I also liked Biscotti in the Four Seasons hotel where the chef comes from Piedmont and there is an open kitchen. I have also tried the highly rated Giusto but was a little disappointed by that place. My local friends talk up an intimate neighbourhood place called Antonio's on Soi Sukhumvit 31, once again an Aussie Italian chef, but I haven't been yet.
Middle Eastern places (predominantly Lebanese with some Egyptian) are all centred around Soi Sukhumvit 3/1. Just head over there, have a stroll and take your pick. We had late night munching there one time (don't remember the name of the place) but the falafel and baba ganoush varietal were very tasty and it's all a good spectacle with hill tribe ladies wandering around in traditional garb selling their wares.