Do you know where machines are in Zurich to change coins for cash, or do we just need to go to the bank teller? Thank you!

Bring them to my market stall, I run out of coins almost every day

You can go to main post office (Near to Zurich HB), they will give you different color pages to pack the coin, pack it and give it to them, Immediately they will give you cash.

Depends if you want to do the coin roll method or not... Most banks will only do it for free if you have an account with them, otherwise they charge you, don't know how much though. I have an account with the post office so I go to Rennweg and chuck them into the machine there, it sorts them, spits out the ones that are "unusual" (often those are very old or dented) and tells you the total that it will be paying into your account.

Do these machines exist at all major post offices?

I think there is coin machine at Credit Suisse near Rathaus/Limmatgehe. You just whack in all your coins, it will sort and count them. But you need a CS account, as the money is directly transferred to your keykard (i.e. no cash out). Have fun!

Some bigger USB banks have a machine, just throw it in unsorted and it counts it all, I have only seen it working and I don't know how your credited (most likely a UBS account) as parking meters or my children's piggy banks get all mine

The ZKB in Dietikon has a coin counting machine.
Just make sure you don't have over a certain limit as beyond that they charge a percentage (on the whole amount!).
The limit is posted. It's something like 500 CHF.

If you have a PostFinance account, there's an excellent machine in the PostFinance branch on Rennweg in Zürich for paying coins into your account. It's at Rennweg 35, 8001 Zürich:

http://g.co/maps/vvm2c

You put in your PostFinance card, tip in your bag of cash into the hole that opens up and it's counted and credited to your account. This is also pretty good fun

Being Swiss I really enjoy making coin rolls and dropping them off at a post office even though my 3 yr old is still shocked that I would swap "money" for "paper"..

Popped in to UBS today to inquire about the same and was told to bring the lot in a bag and they'd charge me 1% for the privilege

Why not just spend it?