Do you invite your parents to visit or do you wait for them to ask to visit?

Do you have an opinion on who should invite/ask? Meaning should the parents be the ones to ask or should the child be asking the parents to come visit?

My mom travels and does lots of volunteer work (she is retired) I am always asking her to come visit and she is always busy so I stopped asking ..... then I get the "well you haven't invited me"

ugh... I cant win!