Barney, what Ruby has said is so true. There is nothing more you could have done for your dad. You were obviously a very loving daughter and I have no doubt at all that he would have known that and appreciated it. From everything you say he sounds so much like my own lovely dad - wearing a tie, combing his hair etc, very 'old school' - and such a wonderful gandad. My two boys were his only grandchildren and I am so grateful for the five years he had with DS1 and the year or so he had with DS2, My dad led a good long life (he was 80 when he died) and the one thing that still upsets me is the thought that my kids will grow up without him. (My fault for not having them till I was in my late 30's I suppose!)
I think a lot of your sadness comes from the suddenness of your dad's death, and the 'undignified'way he died (please don't take that the wrong way, I hope you understand what I mean, and that you haven't had 'closure'. I really think a letter would help. You can burn it afterwards or put it away in a box on a high shelf, whatever. And don't worry about what you say. Just say what you feel. I wrote a sort of eulogy about my dad which was read out at his funeral - I wanted people to know what he meant to me and my family. It really helped that I had written it down and that it was 'out there'. This is what I said:
"My brothers and I will miss our Dad more than words can say. To each of us he was very special and we all have our own memories of him as we grew up. I particularly remember the stories he used to tell us in bed on weekend mornings: Goldilocks and the Three Bears and Little Red Riding Hood especially, and how he could do a very convincing scary wolf voice. There are also many happy memories of holidays on the beach in Wales, when he would spend hours helping DB1 construct detailed irrigation systems in the sand, before finally letting the seawaters flood in. And to DB2 he was an invaluable fishing coach, passing on all his trade secrets from father to son, until the son regularly began to bring home a bigger and more impressive catch than the father.
Each of us can recall countless occasions on which his support and wisdom proved invaluable and showed us the right way to proceed. I have relied on him so many times and I was as proud of him as he was of me when he walked me down the aisle of this church on my wedding day to DH. But perhaps the role to which he was most suited in life was the one he had so little time to enjoy: as grandfather to DS1 and DS2. His love and enthusiasm for the boys, his endless patience with them, and their fun and mutual delight in each other's company has enriched their early lives and I am sure that DS1, especially, will never forget him.
Dad's strong faith meant he did not fear death. He will always be with us in our hearts, and the example of love, patience, tolerance and kindness he set for us will be our guide for the future."