I use different flour combinations, depending on the recipe I'm making. I will often use almond flour and coconut flour, especially with my grain free recipes. As far as using a blend of multiple flours, I like to mix my own blends. I found out early on, that I don't like to taste of most of the pre-made blends that I've tried (although I will have them sometimes).
Each flour has a different weight, and so will influence the recipes differently. If you are substituting flours, make sure that you use one that is of a similar weight. Although the results may still vary slightly if you use a flour different from the original recipe, you have a better chance of it being more similar to the intended result.
Here's a summary from Simply Sugar and Gluten Free:
Heavyweight flours are going to produce a much denser final product. These flours would also be more nutritious than starchier flours. Nut flours are obviously higher in fat but are packed with omega-3 fatty acids and other good-for-you nutrients. Almond flour, regular brown rice, buckwheat, stone ground cornmeal, and any other nut meal (walnut, pecan, chestnut, etc.) would be considered heavyweight flours.
Mediumweight gluten free flours are, on average, more nutritious than lightweight flours. These flours have a little more body and bulk, including amaranth, coconut, garbanzo bean, millet, quinoa, sorghum, superfine brown rice, and teff.
Lightweight gluten free flours, or the least dense, are your starchiest flours and are generally neutral in taste. Arrowroot, cornstarch, potato starch, sweet rice flour, tapioca flour, and white rice flour fall in this category. When I first saw cornstarch, arrowroot, and potato starch talked about as flours, I was totally confused. They’re technically not flours at all but used as such to enhance the quality of gluten free baked goods.
My blends come from Gluten Free Girl's website. The whole grain blend is basically a guide, because the site says to add 700g. of any blend of whole grain flours + 300g. of starches (click on the link for more info). The good thing about being flexible is that, if you run out of one flour, you can substitute it for another flour of similar weight.
Here's my current blends:
All Purpose Flour Blend
150 g. sorghum flour
150 g. brown rice flour
50 g. potato flour
+ 50g. each of 3 of the following:
white rice flour
Whole Grain Flour Blend (makes a large batch)
* Update (11/2/12): I currently use equal parts sorgum, teff, brown rice, and white rice, and will add almond flour if I have some...you can play around with it and use what you have on hand. General rule of thumb is to use 60% whole grain flours and 40% starches or white rice flour.
brown rice flour
+ 150 g. each:
white rice flour