Upgrade question - how does requesting a miles upgrade differ from UDU?
 

I am 1P and I have several long flights in next few months - SFO-ORD-ORD-JAX-SFO-IAD. How does requesting a miles upgrade differ from UDU? Do I get priority over 1k over 1p NOT using miles? No benefit?

The only difference is if you use miles or another instrument you can confirm the upgrade anytime after booking if there's NF space available. Once you get inside the UDU window, a 1K trying to upgrade for free will have priority over you.

so prior to 100 hour window I DO get priority over 1k??
That is to say, 150 hours out if there is a seat will i get it above a 1k waiting for 100 hour window?

Yes - IF NF becomes available outside 100 hours (or 120 hours for GS). If elites are waiting for UDU, they don't have any "priority".

IF you don't get upgraded before your window - call to pull the mileage upgrade and let it go to UDU.

OK thanks---if i dont get the upgrade before my window will UA charge me my miles for UDU (should I get it) if i forget to withdraw the upgrade?

You won't get UDU if you have a waitlisted mileage upgrade. If you clear at that point, it will be with the miles.