hi
I'm a bigger than average guy at 200 lbs. I recently was faced with a similar decision as you. My first thought was just to get new wheels. However, upon inspection I found out that my Ultegra hubs and Mavic CXP33 rims were quite good. I measured the spokes and found that they were a bit on the skinny side. And reading some good threads in these forums led me to conclude I would be better off with a sturdier set of spokes. In the end, I paid a local wheel builder to replace spokes.
I can't make this suggestion to you without knowing what hubs / rims you are using.
But in general, heavier gauge spokes and higher spoke count do make a difference. Results for my wheels were much better. Good luck.