I love Cape May breakfast and would recommend it whole heartedly.
It's been a long time since I went to Brown Derby - it was fine, nothing amazing as I remember.
50's Primetime is fun and the food is good - not fancy, but good.
If you want something a little more upscale for 1 TS at DHS, why not try Mama Melrose? I've always enjoyed the food there.
I would say Cape May breakfast and 1 credt TS is a better deal...HBD just doesn't seem "grand" enough to me for 2 TS.
Also, depending upon your day and schedule you can always head back to the BW area for Dinner...Kouzinna and the Brewery are good for 1 TS.
OR if you want a better 2TS meal...have quick breakfast at your resort or DHS and go to BW area to Flying Fish for 2TS dinner. I haven't been, but have heard nothing by rave reviews about it on the boards. I was thinking of going, but we have a toddler and I'm not sure how his behavior will be and who would want a cranky 3yo (me and other gusts) in a signature restaurant?
Another thought...the dress in signature dining restaurants is usually above normal park fare (shorts & T-shirt). Most people probably go back to their resort after a day in the park to freshen up before going to a signature meal. If you're in the park all day and going right to dinner - a more casual place like 50s Primetime or Mama Melrose might be better.