(strapping on my fake boobs and wig)
I bought a hybrid (27-speed, disc brakes, front suspension) when I first started riding because, like you, I liked the versatility and the price ($600). It's great for riding around town because the streets around here are in awful shape. It's ok for long-distance riding (longest ride I've done on it is 35 miles), but your wife is right--it's very heavy. You'll be working hard on road rides if she's on a road bike. I can average about 14 mph on my hybrid vs 17 or so on my road bike.
But if you get a road bike there is no "mostly" road riding--you don't want to take one of those off road. My opinion is unless you truly just want to do hardcore road riding, go for the hybrid. I probably ride my hybrid more often than the road bike.
/csb impersonation