Our move abroad was discussed at length with our AC- and they were totally for it and actually encouraged us. But we insisted on keeping a small 'pied-à-terre' in the UK, and we plan visits well in advance and never ever invite ourselves.
We discuss when we might go over, and then say if you have time to see us or have us for a few days, we would love to see you. They have space, and never impose our presence, and make sure we never stay more than 5-6 days with either at a time, and take ourselves off for a few hours here or there to give them a breather.
My parents used to come for 3 weeks at a time- and as much as I adored them, it was quite hard, especially at Christmas. Due to OH's work, we were never able to go over Christmas and New Year, they always came to us, and sometimes my MIL too. Bless them.