Hi ExD1938, I don't think you are being selfish at all.
My parents celebrated their 60th two years ago, we also have a sizeable family but we are split between the north east and south west of England, We siblings asked our parents how they wanted to mark such a wonderful event and they wanted a quiet celebration too so we set about organising and paying for a close family and friends BBQ in our parents back garden.
We did all the prep, all the visiting family accommodation, all the cooking and all the cleaning up, our parents had a lovely time and it was a very happy day.
Congratulations on 60 years and celebrate it how you want to, if family and friends want something else let them sort it out xx