Avantages
RAND is a non-profit organization, which is very similar to a university, without students. It has a slightly shady reputation, but that is undeserved (although it might have been deserved in the past). One gets involved in research which is cutting edge, and is surrounded by very bright very hard working individuals. There is relatively generous paid vacation time, and in something that I think indicates what RAND think of their staff, vacation pay is higher (for researchers, not sure about others) than normal pay. That is, if you take all the vacation allocated to you, your pay will be about 5% higher than if you did not take any vacation.
Inconvénients
Coverage. Finding 100% coverage (i.e. 100% of your salary) is the thing that all researchers finds stressful, and particularly stressful to start off with, and for your first year or two at RAND.