For men, I think the sexiest occupations include (but are not limited to) military officer or Special Ops, surgeon, professor, doctor, scientist, detective, or just any career that requires dedication, discipline, intelligence, perseverance, and motivation to grow and to continuously meet new challenges.
But really, I think any career could be sexy, depending upon the person who is playing that role. If he applies himself to doing his job confidently and competently while striving for excellence and treating those around him with dignity and respect, then that is sexy.
The above applies to women, too. It's not always what you do. It's how you do it and the quality of character you have developed.