How do you justify employee spends that don't have an immediate "return on investment"?

Certain benefits offered to your employees, such as group outtings or special meals, go a long way in boosting morale. Team-building activities are a great way to build stronger relationships with and between your employees. 

While necessary, it may be difficult to gauge how much to spend and what the tangible return will be.

How do you monetarily valuate these types of investments? Why are these types of benefits valuable for your business in the short and long-term? How do you justify spending that may or may not have a clear or direct "return on investment" (i.e. ROI)?