I would recommend something special.
A Lagavulin 16 might be out of your range, but a Redbreast 12 would probably fit the bill.
5 Year or older is serviceable, but it is a special occasion. If he's below 25, don't worry, just get him something with volume. If he's older than 25, get him something aged and indelible.
I'm sure no matter what you get, he'll love it.