Adding more yeast can make the bread drier and it doesn't keep so well. It can also give a pronounced yeasty taste, which some people like. You could leave it to ferment longer at temperature, or use harder flour, which will trap more gas and the dough will thus rise higher and be more 'holey'.

If you keep flour in bulk or for any length of time keep it in an airtight container, it can pick up smells from other food and go off, especially the oils in wholemeal flour.