We had a pretty large group between all of us and our little siblings, but Dao was able to accommodate us easily. They take reservations, but I don't think you'll really need them. The main room is pretty large with large seating options. They also have interesting seating in the middle where you can sit on a pillow and all.
The service was pretty good. There wasn't really anything tricky to our party, and no one had any questions for the waitress. Still, the food was brought out in a timely manner, and she managed our large group well. Also, they were willing to do separate checks for all of us.
The cost is the same as pretty much every other standard Thai restaurant. Entrees are right around $7, which is a deal for Streeterville. However, they charge you $1.50 for rice with your entree which I think is ridiculous. They may as well charge for tap water. It's super cheap to make white rice, and it's included with your meal at every other Thai restaurant, so I don't think it's acceptable to charge.
Since we had a big group, we had a bunch of different dishes, but since I had just met most of the people, I wasn't about to reach across the table to anyone's plate. Accordingly, I'll talk about the things I tried, but there will be plenty more pictures.
The Green Curry Beef
The Pad Kee Mao
The Panang Beef Curry
The Beef Fried Rice
The Chicken Supreme
The Pad Thai
My entree was the Panang Beef Curry (and I bought the brown rice on the side). It's supposed to have a rich curry with a peanut flavoring, but it tasted a little too much like a spicy peanut butter. I tried the Pad Thai which was pretty tasty, but it was a little sweet. Arif also gave me a taste of his Beef Fried Rice which was a nicely done dish. Everyone else seemed relatively pleased with their dishes, but no one really seemed blown away by anything.
Since I didn't eat everything I asked everyone else how they felt about their food. The most common response was that it was average and not much more (and I agreed). I'd just had Silver Spoon a week before this, so I felt like I was in a good place to make a direct comparison. Also, since they're both in a stones throw of each other, I think it's necessary to pick one over the other. I'd definitely go with Silver Spoon for food quality, but for catering and groups Dao is the pick. I'm giving Dao 2.5 out of 5 Pearls.