I can think of 2 particularly good values for xONE tickets:

1. Going to Australia from the US. This is a long trip and you cannot upgrade, so you're going to be stuck in coach for a long time. The price of a business class seat to Australia is probably similar to a RTW ticket. Unless you use miles to get a ticket, you're going to be in the back.

2. If your company is sending you across the world in business class, it may be just as cheap to get a RTW ticket if you can convince them to do this. There is a time limit to the RTW tickets (7 days I believe) to stop you from doing quick trips, but you can buy another cheap ticket to get around that rule if needed.

Some destinations are not good for RTW trips, notably Hawaii. Also, you don't want to use your RTW segments on cheap segments in the US like LGB-JFK, but for costlier destinations like Alaska or expensive Caribbean destinations like Barbados.

I think the best value is to make a list of all the places in the world you'd like to see and figure out which of those places is the most expensive to get to. Then try and make a RTW trip that includes these pricey destinations and fly in business or first class. In the process, you will likely make enough miles back that you can fly for free for a while afterwards.