Recommend speakers for a restaurant sound system

Parasound is an excellent choice for your application for preamp and especially power amps. I recommend their new classic line to my pro customers. Also look at Mogami raw cable. They make a co-ax speaker cable that is very open sounding and inexpensive.

Get the license from ASCAP/BMI, you'll have to pay fees to someone and this way you can do what you want, including having live music. (Very frustrating that original bands can't be booked into a place that doesn't pay ASCAP! They are Nazis and will harass you till you pay.)
As for music not making a difference, that seems like saying ambiance doesn't matter. Most people can't/won't articulate their opinion of sound quality but they DO notice. I've seen this for years in pro sound. Most bands don't put much into their sound system because they think the audience can't tell the difference. A perfect example of what really happens was when one band redid their sound using Daedalus speakers, everyone asked why they spent so much money when no one will really hear the difference live? Well they consistently sold TEN times the CD's at shows with the new sound system. People didn't articulate that they enjoyed the show more because of the higher quality sound but they did talk with their wallets!
So good on you for trying to do it right!
good luck,
Lou