I usually visit my local MAC store with my teenaged daughter.
I'm 50, and have had a really busy life, so I really didn't bother with makeup until last year. (At this point, I figure it's a public service!
)
I don't use the bright colors, but loved the N Collection and find a lot of great neutrals. Love the lippies, too, and find a nice range between nudes and scary (to me) bright reds.
I've always had good service from everyone, and I'm certainly no designer-head-to-toe hot fashion plate!
As for whether MAC is marketed to a younger crowd, I don't believe it is. I think it's perhaps just less intimidating than most department stores to a lot of teens and twenties. At that age, I wouldn't have known where to start.