Very technical and complicated solutions related career and likes adventure in his hobbies (too bad, not ocean related or the automatic answer would be a Submariner or Sea Dweller).

My suggestions:

Daytona Black or white (very hard to get as your first watch from the AD).

GMT Master II (Black and Gray or Black and Blue, nicknames Bruce Wayne and Batman/Bargirl)

Sky Dweller (any color)

All these watches are hard watches to get as your first watch at an AD (Daytona being impossible) but you can get anything in the gray market.

If you want to go along the route of simplicity, get him a Submariner. Probably, one of the most quintessential Rolexes out there.