General:
* Welcomeness
* Friendliness
* Kindness
* Warmth
* Generosity
* Courtesy
* Graciousness
* Acceptability
* Consideration
* Attentiveness
More formal:
* Hospitableness
* Guest-friendliness
* Service
* Accommodation
* Reception
Informal:
* Warm welcome
* Going the extra mile
* Making someone feel at home
The best synonym will depend on the specific meaning you are trying to convey.