My best record for upgrades happened in Canada, most stays I got upgrade as LTP (unless they had no higher category rooms like 4P at YYZ. In Asia and Europe I got the typical 1 category upgrade.
With the breakfast definition and lounge opening hours hit and miss in the US - I pick the cheapest FFI/TPS/CY for whatever chain (provided that the reviews are decent), if there is a HIX $10 cheaper than FFI, I'd go for that instead.