Personally, I've had boys as good/best friends my entire life... ESPECIALLY right around your daughter's age, because the rest of the girls "got stupid" ;) right around then, and essentially quit doing anything fun. If it wasn't for the boys I would never have done anything fun. THEY still wanted to go to the movies/ride bikes/play sports/hang out... but the girls...oy. From 11-13 it was only gossip, hair, makeup, whine about their parents, talking on the phone in pseudo valley-firl accents. etc. and pretend they were 17.
My guy friends essentially bent over backwards saying "Thank god, you're not like THEM." (Which a few years later was annoying... because, come to find, if you're a "buddy" you're undateable ... although guys who didn't know I was "one of the guys" asked me out readily enough).
So for ME it never totally changed. If I was hanging out with one crowd of boys, as a group or individually it was never never ever dating, but at the same time if I was with a totally different set of guys it was dating.
The "tell" as far as my parents were concerned was if I was "nervous". If I ran out of the house laughing it was friends, if I was up in my room obsessing about how I looked, it was a date. My mum (looking back on it) was fantastic, because instead of trying to curtail all of my activities, she just watched for my tells.
Talking with her years later, she said that at least with the guys she could count on my good sense, but when it was girls... it was THEN that she had to be concerned. Herd mentality I guess. Apparently whenever I was hanging out with girlfriends I came home with attitude, and I wouldn't call, would get up to a lot more mischief, etc.
Anyhow... that's just my story. Good Luck!!