I'm gonna give this a go.
Athletes
Why they should be tied- Strong, flexible, athletic women who have good bodies and can probably handle some good positions.
How they should be tied- The whole team should be wrapped up in athletic tape, bound back-to-back in pairs and of course gagged with the athletic tape. Seeing them in their uniforms would be nice, but it'd be even better to catch them practicing in tank tops, short shorts, sports bras, etc.
Dancers
Why they should be tied- A bit of a cross between my description of athlete and your description of cheerleader. They tend to have good bodies, are even more flexible than most athletes, and I don't want to stereotype too much but many of the ones I knew were pretty arrogant about it and needed to be taught a lesson.
How they should be tied- Hogtied very tightly to take advantage of their flexibility, with rope, and gagged with duct tape, preferably in their dance outfits. You'd have to tie them up really well, because they're likely to wriggle free if you don't.
Teacher (Alternate take on one of yours)
Why they should be tied- Payback for punishment in class. Why else? I actually have a teacher I had in mind for this one, who got me as close to being tied up by a teacher as I've ever been by making me stand with my hands behind my back in class for a while once--and the odd thing is, I actually liked this teacher. But anyway,enough rambling...
How they should be tied- Tied to their chairs with rope, cleave gagged, hopefully wearing something like a blouse and skirt or something like that. Blindfolded first though so she doesn't see you and you get in trouble for it.
Waitress
Why they should be tied- Got my order wrong again. "I said no pickles."
How they should be tied- Hands behind back, ankles together, cleave gagged, locked in the back of the restaurant. "That'll teach you to get the order right next time."