Well, as one who lived for 30 years in Canada before moving to nice sunny Florida, I can tell you that nothing beats salt. From an owner's liability stand point, they better salt, often and a lot at a time. Of course, that also depends on what type of snow you would expect to get.
If it is all light fluffy stuff, then sand might be OK. But if they get freezing rain, or melted snow freezing at night, the sand will do no good at all. the ice will just build up over the sand giving you nice tan colored ice. Once the ice thickness is greater than the sand particle diameter, you might as well forget the sand was ever there. But salt will keep melting, even if it gets temporarily covered in ice.
Any form of mechanical snow removal will leave a thin layer of snow, which is very prone to melting than freezing. So again, salt is wise.
As for the concrete itself, your best bet is to use a very high quality concrete, say at least 5000 psi. Also, use some fly ash or ground slag to increase the density of the concrete. And make sure you place strick limits on water cement ratio, keep it at most 0.45, preferably .4. And use appropriate entrained air. Basically, follow all the suggestions from ACI 318 chapter 4, and make sure the contractor strictly adheres to the specs. They will always cry about such strict requirements just for sidewalks.
