Michael -- just about anything goes nowadays in ballet classes!

I was told never to wear a leotard over my tights, cause the tights can slip down the legs, making a "sagging" look around the crotch.  

Tights can cover the whole leg, but a lot of ballet guys I know like wearing their tights just below the knee, and just above the knee, and like the length of bike-shorts, and at the length of gym-shorts, and one or two wear them shorter!  Like I said, anything seems to go!  In adult classes I don't think anyone cares; when you're around young kids, I think its best to wear long tights.

I have a bike-unitard that fits great and looks good.  You can try these, too.

The girls (and women) in my class always say they like what I wear, no matter what I wear!  I think they like seeing the male body in ballet classes (I mean seeing guys actually in class, cause usually there aren't that many of us!).  Once you get to know the ladies, they may even make clothing requests.  One has asked me to wear white tights cause she likes they way my muscles look in them!

Whatever look you feel comfortable with is OK.  I don't worry too much about what others will think -- soon they'll appreciate you for your dancing and the person you are rather than what you wear!