You could also credit your miles to Frequence Plus (the AF program). Your GM status with Delta aill give you some perks (priority boarding, etc.) and four transatlantic trips are almost enough to make Skyteam Elite Plus with AF (lounge access on international flights is the main perk here). As long as you're stuck with those fligts you might consider switching programs if you might just continue to fly Skyteam. On the other hand those will be orphan miles if you switch to another carrier later in the year.