Originally Posted by
clifford79
The direct OSL-BKK doesn't seem to have an F cabin, so to make use of the free upgrade, you would either need to connect (e.g., LHR/FRA/MUC/ZRH/CDG), or use it for a Y to C upgrade.
You just beat me to it...
Given that upgrades and lounge access don't matter if OP is already flying J (on SK or TG) and would not be able to fly direct to get and upgrade to F, it seems to me that the only real perk that matters is redemption opportunity. Therefore I still think it is better to chose 1 program that fits the OP's needs...or chose a second alliance and get gold in both. This would give more flexibility in terms of price and availability to fly F (as one would need to route via elsewhere regardless of airline).