I think I'm confused by your one point, weiwuokenan. Why are UA miles valued at $0.02/mile? If that's the case, I think it's still worthwhile for me to use cash and miles to upgrade because I otherwise would spend an extra $23,000 to upgrade to J class.

Can you confirm if this is correct assumptions/math?

Four round-trip tickets in business class would be $33,000 cash.
Four round-trip tickets in the mileage upgrade award category would be $10,393.04 + 160,000 miles. So that means my miles are worth almost $23,000. So that's $0.14/mile which is better than $0.02/mile, right? Isn't that a "good" value rate for miles?

Since the miles are "free" due to regular expenses made on my Chase card, I figure i have to use them somewhere. I thought I'd read here that using them for int'l premium classes "makes the most sense." I recognize I'm not guaranteed the upgrade at all, but it might be worth the "risk" of committing my Chase points to UA miles.

Thanks in advance for your patience with me.

IAH- I tried to read some other wiki posts but I think I only got more confused!