This question is also to do with why one gets charged double for Cloud Service instances, and I believe that the answer in my case is due to the fact that I have a Cloud Service Staging Slot which is actually a seperate VM whereas a WebSite Staging slot is just another website instance on the same VM, so you pay the same.
So to pay for one Cloud Service instance ie around 700 hours in a month, one must only have the "Production" slot, the "Staging" slot must be deleted.
Am I correct?
Best How To :
In Cloud Services you're paying the resources you use, meaning that if you have a Production slot and a Staging slot, you pay for both, as you already mentioned.
In App Service (Web Apps, API Apps, Mobile Apps) we support staging slots (multiple ones, not only 1) in Standard and Premium. Each plan has some Staging slots included and you don't pay anything extra. Standard has 5 and Premium has 20. You can find more information at App Service plans
To pay only for the hours you mentioned, you need to only have either Production or Staging running, not both at the same time. Having said that, with the per minute billing Azure has, even if you have Staging running for a small amount of time until you do a swap, the impact on your bill will be really low if it's only a couple of minutes each time.