Booking the ticket for her is the way to go, but your silver status doesn't really come into play unless you are traveling with her.
Personally, I would put a value of 2¢, or at a minimum 1.5¢ per mile used - my minimum "value" for booking a personal award ticket is 1.75¢ per mile (i.e. I wouldn't use 25K miles for a domestic ticket unless the cost of the ticket was close to $500, or more).