yes nice models and would look really good rendered i am sure. there are also rendering programs that work inside sketchup, like podium and v-ray. i have used v-ray and think it's pretty good. but also, i am no rendering expert.
another thing, there is a "render this" competition on this site every so often. maybe if you could see how much difference a good render makes on your model you'd want to do it too!
can you show us your models as wireframes too please?