If you are asking this question I assume the obvious answer of -- "buy them" -- won't work as your job isn't paying for business class.

IF your work is paying for business class, I might consider another carrier -- like Cathay via HKG or ANA via NRT -- with a higher quality experience; personally I like the UA BizFirst seat but the rest of the experience doesn't even compare most of the time.

If your work is NOT paying for business class, flying 4 times a year RT won't get you in a great position to upgrade with Cash+miles; upgrades are done by status and you won't have very high status. If, however, you are flying 12x a year, then you should earn 1K status after 100K miles flown, and then you will be able to upgrade with GPUs.