Receiving my direct commission as a civilian (14+ yrs prior service w/ 2 yr break), is it still appropriate to do the "silver dollar salute"?

Although saluting the flag while in civilian clothing is appropriate, your commissioning ceremony is formal and earns the respect of being in uniform. As you will need to buy your uniform anyway, I recommend the following:

1. Get a haircut and a shave!
2. Get a uniform
3. If your recruiter is an officer, please ask him for an introduction to his/her Senior NCO
4. Prior to your commissioning ceremony, present yourself to the Senior NCO for corrections
5. Attend the ceremony with the grace and dignity you learned as an NCO
6. Pay for your first salute with a silver dollar (you can find one on Ebay for about $20)

Finally, I went through this same ceremony as an NCO. I attended the commissioning board as an NCO and left the board as an officer. When I returned to my unit (an NCO Academy) to out-process and render my first salute, my fellow NCO instructors accepted my salute and I passed out 6 silver dollars. Welcome to the Medical Service Corps. Feel free to stay in touch, if you would like a retired MSC as a mentor.

I think you should be in uniform when the silver dollar salute (first salute as an officer) is rendered.

For an informal ceremony such as the one you describe, it would not be inappropriate to be saluted in civilian clothes and the first salute always merits the silver dollar!