I think you can still get a guaranteed flight slot in the navy, and most other services (except the USCG).
I would probably not just join the navy and let them assign you a career. More so than the other services, the nature of the training and work environment vary dramatically between specialties. You should be able to get a guarantee for something of your choosing before you sign up:
Naval Aviator (Pilot)
Naval Flight Officer (backseater)
Surface Warfare (conventional or nuclear)
Submarines (nuclear)
Special Warfare (SEAL)
EOD/Special Operations (diving)
These are all warfare specialties, for staff jobs (Intel, PAO, Law, Medicine, etc) you need specific relevant civilian education and/or certification. Intel would be open to a variety of college majors I think.
If flying is your primary interest, consider all of the services, not just the navy.