9:15pm??? Good grief! You'd be done eating at 11 at night That worked fine for me in Spain 4 years ago, but now......I'm SO not into eating a full dinner that late. In fact, the "dinners" in Spain are very light and more like lunch.
I think 2 main dining rooms each with 2 seatings and 1 of those should be the 7:30-ish time frame. Definitley good suggestion in my opinion.