Another thing that's changed from when your mom used to color her grays away under the cover of darkness is the quality of the products available. It's been a long time since anyone has gotten even a whiff of any strong, offensive smelling products in salons. Those have long since disappeared or been replaced by gentler formulations that are free, or mostly free from ammonia, peroxide or other harsher chemicals.
Before having any kind of color applied to your hair, select a salon with a certified color professional. Not every hairdresser is an expert in color. Find a salon that specializes in color and ask about the qualifications of their staff. Usually a high end colorist will charge more, but it's worth it. Considering you are looking for something for the holidays, think of this as a gift to you.