I'm not an UA expert(just join mileageplus for 3 years and first year of being 1k) but just some personal experience.
I won't use miles for upgrade on international routes since I feel like paying both cash and miles for upgrade is just not worth it.
Everytime I book an award ticket I would first figure out how much it is to purchase the same ticket by cash. I somehow think the cost of 1 UA mile is 2 cents. In your case, 4 round tickets cost you 240000 miles and $240. The cost of 240000 miles is $4800, and the total cost would be $5040. Therefore, if the price of just purchase the tickets is less than $5040, I would just purchase the tickets using cash. Also, to upgrade all 4 tickets cost you 550*2*4=$4400 and the cost of miles is $3200, makes a total of $7600. If the cost of purchasing business class tickets is less than $7600, I would also just directly buy the business class tickets. And you can just use your 225k miles for future use.
The reason behind that is I just booked an award ticket using 160000 miles for my GF, the route is SAN-LAX-TPE-TXN(Huangshan, Anhui, China); PVG-ICN-SFO-SAN, LAX-TPE-TXN is operated by EVA and PVG-ICN-SFO is operated by Asiana (two 5-stars airlines providing much better in-flight service). The cost of 160000 miles is $3200, and to directly purchase the same ticket by cash would cost me more than $4500. So I feel that the award ticket save my a great deal of money and this kind of award ticket is worth it.

Maybe helpful to you, and please forgive my poor English.