Well, here is my two cents.
I think that I know what you are after - but obviously we do not know your personality.
So: here is what I recommend - and these reps are good enough that you would look both sensible, young, and yet still have taste. You just have to decide what "taste" you want to portray:
1. Tag Heuer - Aquaracer - sporty diver, outgoing, enjoys his free time, active
2. Ebel 1911 Disco Chrono - sporty - racer, not necessarily "outdoors" on weekends - but always doing stuff
3. Rolex Sub - everyones got one. And, there is a reason for that. Problem is, every young guy who believes he has "arrived" gets one.
4. IWC - Slevin - sporty - but more sophisticated - the guy is more knowledgeable that one would think. Those in the know, know.
Can't go wrong with any of those. Can't be called out on any of them either. They are too good.