@cell what zoom are you using and what problems are you running into?
@cell primes are awesome. I use a 24/2.8, 50/1.4, 60/2.8 macro, and 500/8. some day I will afford a 24-70/2.8 like yours. a fast prime lets you do lots of things like: low light, super shallow DoF, and buy more lenses because they're less expensive. oh and they're often smaller. the 50/1.4 is my favorite and default if I can only take one lens.