Originally Posted by
iwillflytheworld
A *G benefit is extra luggage (20kg where weight concept applies, one extra piece where piece concept applies. In many cases the limit for each piece is also higher although this is not official).
I believe neither ST nor OW offer this benefit, though I'm happy to be corrected.
Skyteam definitely don't offer it (though they do offer the yellow 'priority' tag that helps you identify your bag after everyone has gotten theirs).