Where should I take Dad?
Kinkeads would be my first choice for straight seafood. And, most of the upcale steakhouses also have great seafood. The Palm and Mortons are standouts in my mind for great steaks AND seafood. However, I'm sure others will disagree (and hopefully offer suggestions.)
I do know that the Palm often runs promotions for an entire meal special that end up being a pretty good deal. I would call to see if they have something like that.
One think to note is that the DC branches of these restuarants are far better than the NoVA locations.