Originally Posted by
Brobbel
It depends on your flight pattern.
For example: when you book mostly short routes, Flying Blue is an option. With Silver (=ST Elite) you can access lounge for a fee.
With Gold (and Platinum, both ST Elite+) you can access the lounge free with a guest. Lounge access only when you have a Skyteam international ticket.
FB Silver can be achieved with 15 flights (=sectors)
FB Gold is 30 flights, FB Platinum is 60 flights.
Mileage earning however, is very low when flying low-cost-tickets (mostly 25% earning, sometimes even 0%)
If it is for lounge access only, you can also look at Priority Pass.
AFAIK the FB offer of lounge use for a fee for FB Silvers is only good for AF/KLM lounges.
DL AmEx cardholders can purchase a $25 per person admission to DL SCs. DL passengers can usually purchase a discounted SC day pass during OLCI. There's also a one month membership.