Have you asked your sons? Is there any reason why they would want to come? What if you die in another country?
I had these discussions with my daughters a few years back..............No, they have no wish to attend the cremation (in itself very difficult because the Thais don't hang about lighting up that fire). No, they do not want my ashes sent back to the UK (they believe that I as I have chosen Thailand as my home, it is right that I should be cremated there). My Will states that I wish to be cremated in the country in which I die - saves any ridiculous repatriation costs.
When I am dead, I am dead, and my daughters share my belief that life is for the living.
My Will also allocates GBP 1,000 for a 'family' celebration of my life and a small memorial (if they want one) at my UK crematorium.