So many questions! I have so many answers!
1) Setting: I am a fan of something with a little extra sparkle, when KappaStarBoy comes up with my ring, it will probably have sapphires on the sides...he says they go with my eyes, how sweet. Of course, you can NEVER go wrong with a Tiffany-style solitaire. A lot of it depends on your lifestyle. Now that I spend 2/3 of my day at a desk, I can get a more elaborate ring. However, I used to be a percussionist and music teacher, and an elaborate ring would have been hazardous.
2) What looks good together? I like side stones that complement the shape of the center stone. Square sides usually look funny with a round center, round sides look good with pear, oval, and other rounds. I myself want a box radiant or emerald cut, so I want baguettes (the long skinny ones set sideways) on the side.
3) Caveat of three-stone engagement rings. The value of the stones is often split between the three stones. A 1-carat solitaire is much more valuable than 3 1/3-carat stones. If I were you, I'd insist on a center stone that you choose yourself, choose the setting separately.
I could go on for a very long time, but instead I will give you some librarianly advice. Go to the library (or bookstore) and get yourself two books:
How to Buy a Diamond: Insider Secrets for Getting Your Money's Worth by Fred Cuellar, and
The Diamond Ring Buying Guide by Renee Newman. Both are fabulous diamonds-for-dummies books.
PM me if you want to know anything else...KappaStarBoy and I have been doing a LOT of research on this lately. Also, to check out settings and diamonds, visit the
DeBeers site or
Blue Nile.