I personally like simple (like Rachel's she just got!). My mom's first ring is very gaudy (IMO) and her second one has a single diamond, but the setting is too high. I'd constantly be scratching myself and catching it on things. My ideal ring would be a band with maybe stones set IN it.

If she has the same taste as you then I'm thinking you can't go wrong! I'm sure she will love whatever you and he choose.
I know I'd like ANY kind of ring from my boyfriend (after 10 years!!).