I'm 50 and just bought my first RM, a mini Nikki. Yes, the 20-something girls all look great with their RMs - but 20-something girls tend to look great in anything!
The Nikki, Morning After, Shopper & Devote totes would suit absolutely any age; I love the Mom & Grandma photo! Some of the studded, smaller, and cross-body models would have to suit your style, as they would a younger person.
I think us slightly older ladies are a great market for RM. We can remember when it was hard to get bags that weren't black or brown or dull, so peacock and mint and teal and seaglass just blow our minds! We've had longer to get over the whole designer monogram bag thing, and can let a bag's style and leather speak for itself.