So I'm buying her a vibrator.  Any recommendations?  Which do you ladies prefer and why?

My personal favorite)

A rabbit-like vibe/dildo combination is best for both- lots of options for clit stimulation only (Magic Wands, mini wands, eggs, hundred dollar little Swedish ones like Lelo and jimmyjane). I need both areas stimulated to cum and have worn out many a rabbit in my day, hahah. Have fun, and very cool of you!

capable of getting a woman really wet, the most effective was a Mercedes SL.

...He was The Big O before it was called The Big O.

Yes you do ;-p

I find the hitachi is a bit too much for me MOST times, but I squirted (& I'm not usually a squirter) the last time I had one used on me so I also kinda love it!