Originally Posted by
ashley1245
I'm seeing J3 available on the EWR-ZUR leg, J9 available on the IAD to ZUR leg, and J7 available on the ORD-ZUR leg.
No you’re not.

(For one thing, Zurich is ZRH, but that’s not what I mean

.
What you’re seeing is the J inventory on your connecting flight. When you search for connecting flights, in most cases UA will marry the inventory together, and you’ll get a harmonized set of inventory values that match exactly between the two flights. In this case, your XXX-EWR flight is nearly sold out up front — maybe on a regional jet with only 6 F seats? — and that’s affecting the inventory you’re seeing from EWR to ZRH.
Originally Posted by
ashley1245
I'm wondering what my best strategy is for getting a decent cash upgrade offer. Does anyone have any wisdom about which connecting airport would be best?
Should I buy a cash economy ticket (refundable for 24 hours) and see what the immediate cash upgrade purchase price is at checkout?
Should I reserve a saver economy ticket using miles and wait to get a cash upgrade offer?
Not enough information. The best offer is likely to come from the flight which has the most inventory in the
discount business fare buckets. Search the three flights individually — EWR-ZRH, IAD-ZRH, and ORD-ZRH — and look for the inventory values. The further they go before you get to a zero, the better. Business class Inventory is J (JN) C D Z ZN P PN PZ IN I. (JN always equals J). You’re likely to find lower prices on something with inventory at least through P.
What do you consider a “decent’ cash upgrade offer?