I think you could perhaps do with another prime lens, and in my opinion anyone who photographs people needs to have an 85mm prime or a 100mm prime. The Canon 85mm f/1.8 is excellent for portraits ranging from headshots, full bodies, and small families. This lens renders a beautiful out of focus background with minimal feature distortion. The Canon 100mm f/2.8 Macro USM is also an excellent portrait lens. I generally only use mine for headshots and closer portraits because it captures excellent detail with no facial distortions even for super close portraits/headshots, but I imagine it would also be fine to use for full body portraits and small groups. Personally I don't care for portraits taken with lenses much longer than 100mm, but the Canon 135mm lenses are the exception for me, if you decide you want something longer.