Source for this image here.
Recently I have been baking our bread using spelt flour instead of our usual mixed granary flour. We've all liked the results so far, although the texture of the bread is a little different to ordinary wheat flour. I find it to make a softer loaf, that rises well but perhaps not quite as well as wheat loaves, and with a softer crust also.
It has a mild, slightly nutty taste (not at all like buckwheat, in fact not a wheat grain at all, which is also used as a substitute for wheat flour and in fact does not contain gluten at all. I don't like the taste of buckwheat so we don't usually have this) and in appearance, when ground, is almost identical to wholegrain (graham) flour. It's a little more expensive to buy than ordinary flour (probably because it isn't as popular, therefore it's not as mass-produced) but I can get 3 loaves out of an ordinary 1 kg bag so it's not too expensive - about £3 a bag in England.
As another alternative to ordinary flour I also often use rye - which is another grain closely related to wheat. Rye also has a lower gluten content and isn't suitable for making into bread when used exclusively. I usually combine it 50/50 with white bread flour, and it produces a very pleasant, springy, well risen loaf. For a long time "rye and white" was our regular, standard loaf - but it's always good to have a change!
Other flours that I would like to experiment with include oat flour and brown rice flour, which makes a very pleasant, light, short textured loaf when combined with other grains. None of us need a gluten free diet, and while most of the alternatives to wheat flour are not only expensive but also require other ingredients not otherwise needed in breadmaking such as xantham gum and alternative sources of fibre such as flax seed, it certainly doesn't do us any harm to try low or gluten free wheat alternatives, and while I don't intend to substitute them regularly, its fun to experiment, and so far, we have really enjoyed the results!