You can get creative to increase your upgrade chances, esp if you're willing to connect, but I know you're not keen on it. But still, I'll share some of my success strategies. Perhaps LAX/SNA/ONT/LGB-SLC-JFK where a PM has a very good chance of the upgrade (I've never missed either way between SLC-JFK and even seen empty seats in F). If going to ATL, maybe try an LAX-MEM/LAS/PHX-ATL routing (the LAX-LAS/PHX-onward connections aren't showing up the way they were a year ago though).
I've only flown in F LAX/SNA-ATL if I've paid for it (and with FCM it's become much easier to justify). I have gotten upgraded ONT-ATL the two times I've taken it. And only made JFK-LAX on a Saturday night and LAX-JFK on the 6:30am on a Tuesday following a Monday holiday, otherwise sat in the back.
The difference between Gold and Plat isn't what it used to be, but it is definitely worth it in my opinion.