That's not really my experience. Opposite-sided castling seems fairly rare and in those cases where white can sort of force black to do so it is usually not so much in white's own interest (e.g. in a lot of those Nxf6 & gxf6 lines white's best usually involves castling long). The variations that have the best reputation for white (e.g. see Tiviakov's recent article) often involve both sides castling long and white trying to positionally grind black down (unless black goes wrong and gets himself into tactical trouble, which is always a danger when white has a lead in development).

I guess you are thinking of the lines where Sf6: happens and Black takes with the g pawn? Black ends up with the very strong Caro-Kann style diamond shaped box of pawns on light squares with an open g file and long castles. This is great position to attack from and Black should enjoy this. Am I on your wavelength? This normally arises from the 8. Sd5 or 8 Se4 lines.

Regards, John