While that's a lot to go searching for, the good news is that it can all be found on the same single search results page, and there are no special custom profile settings or parameters that you need to set, though there is one which can help, detailed at the end of this post.
So, here's the drill, and it really is quite simple.
Do a normal revenue search for the flight you're interested in. One way or round trip doesn't matter. You just need a REVENUE fare search page that shows the results for the flight/date you are interested in.
On the results page look in the right-most column. The third row should say something like "Fare Class: United Economy (W)" on it. Note that the words Fare Class are a hyperlink.
Click that link and you will see all the inventory buckets for the flight:
That's all there is to it. Piece of cake.
If you want to get a bit more fancy and make it even easier - AND if you have a browser which supports GreaseMonkey scripts - I've created a script which causes the inventory to always be displayed for all flights and which highlights the award buckets. The downside is that there is no "X" button to close it and it obscures some other information, but I like the inventory info more so that's how I roll. For more information on that script check out my post here. Version 6.1 of the script is the first to support the new United.com and PSS site in it; older versions need to be upgraded.
This is what the page looks like with the script enabled:
Note the red/green coloring of the award buckets. Easy, at-a-glance information on upgrades and awards without too much effort at all.
sbm12 - Thank you for posting this helpful information in one place. This may need to be a sticky for a while. Can you clarify: I understand R is coach -> business. This used to be NC, I assume. What is the difference between R and RN? Also if someone could comment on what I and X are, or provide a link, that would be useful
Edited to add: This would mean the "ozstamps" thread listing all UA revenue and award booking codes is out of date, as it states (among other things) that R=XF.
Last edited by restlessinRNO; Mar 4, 12 at 8:06 pm.