To start off, most of what you consider "r&b" today is not r&b, but hip-hop, there's a difference. R&B originated in the 60s, and still exists today, despite what people say, in good form. However in the 70's, much R&B took a funk-style twist to it.
It usually has mellow or laid back beats and rhytms to it, and quality vocals for the most part.
1) Hey let's listen to some motown, classic 60's R&B!
2) Hey let's listen to some Isley Bros., some good 70's R&B!
3) Hey let's listen to some various artists, true 80's R&B!
4) Hey how about some Aaliyah for some great 90's R&B!
5) Hey how about some Foxy Brown for some good modern R&B!