I'm pretty similar in that I'm not into Greek - well, receiving, anyway- but like to play with plugs once in a while. They're a lot of fun while being spanked; the two sensations amplify each other wonderfully.
If you want to play devious, a game I like is to put one in that you know will be too small. Have her clench it in while you're spanking her, and if (when) it pops out, punish her accordingly!
(If you want to get *really* devious, try figging and caning at the same time
Vibration is great for relaxing the muscles, especially if you choose a plug that may be a bit bigger and more of a challenge to get in. Of course, everyone is different in what sensations they prefer. She may find it overstimulating. The only way to find out is to try everything!
I would suggest alluding to your plans before you meet so that she can veto if she so chooses. If she's excited by the idea, that'll leave you in the clear to assert your domliness, while of course respecting safewords.
For beginners, I highly suggest the pink pop plugs by Doc Johnson. The small is VERY small, so I'd suggest checking them out in person to avoid size discrepancies. They're cute and really well shaped for your purposes- they don't vibrate but have a ring at the end that you can stick a bullet vibe into if you want. Many of the nicer sex toy stores in NYC stock them.
Hope this was helpful, and have fun!