How do I get the best possible texture when making vegetable cream soups?
You could always blend before you strain.  I find that when making soup of all kinds that a few minutes with my immersion blender does wonders for the final product.  Not only does it puree all the solids into much smaller chunks, but it also makes sure that all the liquid is a homogeneous whole.  

After blending, I also tend to strain just to get out anything that I might have missed.  I use a fine mesh strainer and a spatula to force the liquid through quickly.  I also own an old flour sifter that I have used quite a few times instead of the strainer, but it doesn't offer any real benefits over the other.