I keep half a dozen client letters in a folder in my word processing program, and use the one I need depending on whether there is a refund or balance due on the 1040 or state return.  Occasionally I have to do an edit if there is more than one state, or a credit elect.  I also change the date manually, because I don't know word processing well enough to use a template for that.  This puts it on my letterhead (which is used for all communications); if I wanted color, I could do that.  I also print the letters on a different printer, with different paper, from tax forms.  Maybe I put too much time and effort into this, but I like the way it looks.