Thanks for your replies. My preference is to use solid wood or real wood. I understand that one of the reasons for engineered wood for doors is so that they do not warp, but think is probably less likely to happen with floors unless you get a leak (we are planning a wooden floor in the kitchen, but will probably have the current deal floor under kitchen units, sink, washing machine, etc.).
Is there much of a difference between engineered and semi solid - I have looked at both and they seem to have a layer of oak, for example, on top of plywood or something similar.
Cost is also a factor for us.