Genuine personalisation can really make your stay.

A card with "welcome back Mr Stut" scribbled on over the dots doesn't do that much for me.

Thoughtful gifts or recognition (e.g. non-alcoholic drinks because they know I don't drink, pre-arranged cycle hire because they know I always use it, poached eggs/dosa/whatever immediately offered for breakfast because they know it's my favourite - even in once case, invitation to breakfast with one of the hotel managers), now that goes a long way.

There was an average, slightly out of the way hotel in Amsterdam I used to keep going back to, because they were so welcoming and good at this kind of thing.