In my Denmark game, I inherited England and Hungary and was going to inherit France when my mother died. I had just begun my reign and I saw that the vassals in Hungary (very far away from Middlesex and it took a LOT of time to get there as it is landlocked) were getting restless, so I gave it away to my brother (who was a duke there and was the most restless).
That solved a lot of problems, firstly, I could concentrate on troublesome vassals in England (and later, France) while my brother did all the legwork in Hungary and now, 150 years later the rulers of Hungary still respond to my alliance calls, with the only downside being I had to help them twice, once against the Mongols and once against HRE. Had I tried to kept Hungary, I would have had to spend first 10 years of my reign ferrying troops between England, Hungary and Denmark crushing one rebellion after another and this would be repeated everytime I had a new ruler. I thought it would be too much of a bother.