Mikej, what part of the country do you live in? IOW, is this fireplace for heat, or just for fun? If you're in a warmer latitude then the ventless type might make sense. The house we bought in Vermont had a wood stove and a gas fireplace, in different rooms, and we use them both. The gas fireplace is a direct-vent type.
Why is your wife interested in ventless? Take a look at these drawings for a nice explanation of direct-vent vs. ventless:
http://www.thisoldhouse.com/toh/phot...859246,00.html
http://www.thisoldhouse.com/toh/phot...859250,00.html
The part about ventless being banned in California and some cities would be a deal-breaker for me.