If the CBs are embedded with tops below your svc ceiling then go over the top of them.
Flying over the top can be a bad idea. If the CB is still developing, it can grow very rapidly (faster than you can climb). If its surface looks very crisp and well defined, only fly above it if you can stay well above or if your plane is fast enough to get of its way pretty quickly.
Lots of interesting stuff about CBs here:
http://www.ais.org.uk/aes/pubs/aip/p...4_P_081_en.PDF
Mark