I had the Behold, and I now currently use the 8900.
There is absolutely no question which is the better phone. Get the 8900.
The UI on the Behold is sluggish, the display is worse, and I dropped calls left and right on that thing.
The Behold is 3G, while the 8900 is not, but to me, the 8900 is still faster, has better reception, and the calls seem just as clear, if not clearer.
If your wife is set on having a pink phone, get a pink gel case for the 8900. They're only $9 bucks at a corp store, and I'm sure can be found cheaper elsewhere.
8900 all the way.