I am wondering will having a 7.1 configuration sound any better than a 5.1 system?

I ask this with this motive. I am getting the Epic 50 or the Epic 60. THose are all 5.1. I am allowed 4 speaker prewires in my new home by the builder. I am not going to prewire the fronts because the wires will be behind the entertainment center. The rears will be wired to the wall. That leaves me two speaker wires left to place.

Should i use those two speakers for 7.1 or should i have them wire those two speakers on the second floor for all around sound in the home? Thanks yall.