I suggest a pair of new speakers. If size isn't a major concern a pair of Vandersteen 2Ces would be perfect with your current system. Later you could add a matching center, etc. as you like.
I think it depends on your budget. You have decent front speakers, and fed the right amplification, can sound very good. I don't think you are currently feeding them enough power. I would try to find a used Classe 200 wpc amp. I don't think you are acheiving what you really want when you bi amp with those Rotel amps.
I think they will come alive if you give them enough power.
I think you should consider S7horton's idea of a Classe 200 for the front channels and then you can use an MCA30 for the center and surrounds. I assume you have a combo music/HT set-up. I have similar equipment for my HT setup (AVM2 plus MCA30) but I use the HT pass though on the AVM2 to run the front 2 channels to my MAC tube amp. My main 2 channel music setp-up is a MAC tube pre and amp. I listen to 2 channel way more than HT so the set-up is great. I've owned B&W speakers and also a Classe 200. I think they would be a great match. I'm not so sure the MCA30 is a great match for your B&W's.