My DH's parents emigrated to New Zealand about ten years ago. Since then he has met, married and had two childen with me (a 4yr old DS and 10mth old DD).
My parents in law have visited on three occasions in the last four and a half years (once for the wedding, and once when each child was born).
We can't afford to visit them so the only other contact has been phone, webcam and letters, which don't really work.
Every time they do visit my DS gets spoiled rotten by them and then is increasingly bereft when they leave and we have to deal with weeks of questions like "why can't I see nana and grandad, I really miss them."
We have asked them several times to consider moving back so we can all enjoy a closer family relationship but they will not consider it.
We live very close to my parents/siblings so we try to make the most of that.
I know this sounds harsh but if there is no chance of our children having a proper relationship with their long distance grandparents, we are seriously considering asking them to stop all contact with them, as it just causes more upset.