C.M.
Fort Worth - Reata has a glassed in room that would be nice for a gathering. Though food is yummy, it's also pricey
Brio (sp??) - in Southlake Town Center. Nice italian and a room in the back you could host the part. Love this place!!!
Dallas - Maggiano's LIttle Italy - super yummy; they have rooms you can book and you can also order "family style." Great location and menu for larger parties. (Hwy 75 and Northwest Hwy - Northpark Mall)
I would think all have websites.
Good luck!