Since you already have the 18-200mm you might as well use it.
Keep in mind that venues of dance do not always allow flash. So you are going to really have to practice ambient light photography with your 18-200mm.
I would suggest the 50mm f/1.8 but, unfortunately, the D60 lacks a screwdriver and will not focus the 50mm f/1.8. You don't mention your budget or the type of dance but if this fits the bill it is something to consider: Nikkor 50mm f/1.4 AF-S.
Keep in mind that venues of dance do not always allow flash. So you are going to really have to practice ambient light photography with your 18-200mm.
I would suggest the 50mm f/1.8 but, unfortunately, the D60 lacks a screwdriver and will not focus the 50mm f/1.8. You don't mention your budget or the type of dance but if this fits the bill it is something to consider: Nikkor 50mm f/1.4 AF-S.
