Is a 60 day non-reneweal of Lease for rental sufficient?
I would think it was. You should be able to find new tenants in that period of time. If you are writing a new lease ninety days would be better of course.
Depends on whether you are the Landlord or the Tenant. If you are a Landlord you would want to push for a 90 day notice, if you were a Tenant I would suggest between 30 to 60 day notice - depends on if you have something else lined up or how long it will take to move.