That it also comes with a substantial pay rise, zero travel and the opportunity to work on stuff I actually find interesting is just a gigantic cherry on the cake.
It was by far the largest factor in getting me to go look elsewhere though not the only one.
I was frank (though polite) with my boss (since I'm a lead and I have zero intention of ever returning) about it - they are going to haemorrhage their senior developers and I know stuff he doesn't yet about others leaving.