Reputable singles cruises to Europe?

Question

Looking for a singles cruise where they won't gouge me by 200% of the room rate, and where it's just singles in their 30s and 40s on reputable cruise lines. Just interested in Europe. Anyone out there who has been on one of these cruises? Is it fun? Classy? Pls don't just refer me to URLs...want to hear your testimonial. :) Thanks!