[aigel]

Government
You'll be bored stiff working for the Government. Sure, it will be a "safe" job with lots of spare time, but you will waste away 8-5 which is still the majority of your day. I'd save this for later when you may want to feed a family reliably and settle down with little stress at work.

Military
Not sure if this is your cup of tea, but that would be a little too structured for me. I like to put myself through challenges but I'd rather do this on my own than with the help of a drill sergeant. This may be nicer with an advanced career but then see above "Government". Seeing the world won't be at your pace either.

Gradschool
How about grad school in an engineering or science field. But not to the lab down the street. Go find a grad school project that is somewhere else. A large science project - telescope, particle accelerator experiment, nature study etc. This will not cost anything and certainly will put you ahead with specialized knowledge that should land you a decent job either in academia or engineering.
I hear what others are saying about grad school not making a difference in their professional lives. This may be true in some areas, but certainly not in science and engineering. Look at engineering job ads - most the six figure salary openings specifically ask for an advanced degree. Getting a degree in a technical area proves that you have stamina and can independently focus on one project for an extended period of time and finish it.

Own Businesss
Entrepreneurship is a hard one these days too. Be it the small business in basic service industry or the venture backed tech start up. There is less money spent by consumers today and venture capital has dried up pretty well. No way you'll get a foot in the door with VC unless you have extremely good connections on top of a fabulous business idea.

Automotive
What happened to the engine rebuilding hobby? Why not take a job at a major hot rod shop in the Bay Area or L.A.? Work for a while 3-5 years, learn and then start your own thing? A lot of the tuning business has gotten complicated enough where you will benefit from a technical college background. This can be a Porsche place, a race team, Ferrari / Lambo specialist etc. I would think that being an apprentice there would be fun and pay the bills for a while until you decide on how to proceed. Many of the best mechanics and specialty shops in the Bay Area are former race team mechanics. They all look to have fun and make a decent living.

George