I used Minoxidil for a year and didn't do anything for me. Plus it was a pain to use. Twice a day, and it got into my hair and made it look funky. They made a mousse version, but wasn't any better, and I don't think it got onto my scalp as well as the drops. Doesn't hurt to try, either. Just don't expect quick results.
I went the Finasteride route and it made a big difference. Was on it for 2 years. But be prepared for side effects.
Graying, on the other hand, is a hair of a different color. 🙂