I'll chime in.

Being LAS based, upgrades are pretty easy esp. for me as a leisure traveller primarly on NWA. I fly LAS-MSP/DTW-CMH often. MSP/DTW-CMH and vv is an easy upgrade, even as a silver/gold.

MSP-LAS and vv is actually a decently hard upgrade (I'd say I miss 5-10% of the time). DTW-LAS and vv is actually easier than MSP as I cleared more on that route as a silver and gold.

MEM-LAS and vv is very easy, though I did miss once as a Silver. The AMS-MEM flight feeds a lot of connecting traffic to the last flight of the night to LAS.