Welcome to FT, vtski!
I'll attempt to spare you of "lingo" in this post, but the lingo you see here honestly isn't that hard to decipher (e.g. if you see an airline code that you don't recognize, simply plug it into Google).
1. Your plan seems okay to me, as outlined, but if pulling off the return without hassle is a top priority, you might want to consider an overnight connection; this would have the added benefit of giving you a chance to see Beijing
2. But, Air China has two flights to Los Angeles, so if the 9p doesn't work out, they would protect you on their afternoon flight the following day
3. On the outbound, you would need to clear customs in Beijing, which necessitates picking up your bags
4. Business class doesn't entitle you to many special favors in either direction
5. Following are better routes between Los Angeles and Guangzhou
-China Southern (NONSTOP)
-Eva or China Airlines via Taipei
-Korean via Seoul
-Cathay Pacific via Hong Kong, though the return portion of this is a little dangerous if you fancy a reasonable connection
In closing, I want to reiterate that your original plan seems reasonably sound to me; just don't bet the farm on pulling off the return because if you happen to experience an 8 hour delay on Guangzhou Beijing, you will obviously miss the 9p flight from Beijing to Los Angeles.