For what it's worth, here's my opinion. I don't know all the ins and outs of your situation, so this may be miles off the mark. Letters are so impersonal IMHO - any chance you can just show up with a couple of McDonald's coupons and offer to take your Dad out for a burger and give him a hug? And then just tell him you decided to do it for the simple reason that you are still here on this earth, he is still here on this earth, and there's no time like the present to reach out and touch your most dearly beloved? If he says he can't go, so be it but you made the effort. 100% BETTER than any card or letter...again just my 2c.