Israel Vibration was Bob Marley's favorite reggae band.
Check them out. Black Uhuru have some great dub stuff. Max Romeo and the Upsetters are good as well for a classic Reggae feel. Junior Murvin (not to be confused with Wailers guitarist Junior Marvin) did some interesting stuff as well, most notably the song Police and Thieves, which was covered by the Clash on their first album. He has a really high voice, and his music is good to relax to. If you want to really sample some old school reggae, get yourself the Lee Perry box set. Perry was a producer who did stuff for pretty much all the reggae bands and pretty much invented dub. As a matter of fact, if you get the Perry box set, you'll be able to hear stuff by all the above mentioned bands, as well as Bob Marley and others.