have been looking at used gl550s and trying to decide on what factory options I should insist on and what I could live without.

Thanks for your help!

If you're thinking about towing something now or down the road, be sure to buy one equipped with the towing package. Retrofitting is not a viable option.

Just went through this myself. I'm coming out of a TDI Touareg, which was very tossable, and downright Panzer like with snows. The 550 takes an extra second to set up for spirited moves, and I don't want to risk any body work damage in the winter, so I'm now searching for a 19" set-up. The only tire looks like a Nokian WRG3.

The 550 comes pretty well equipped out of the box. Mine has everything except: B&O, night vision and illuminated star. If you are a spirited driver, Active Curve, it's expensive and rare, but really helps with lateral g's. The driver assists are too noticeable. I've turned some off. The 360° camera is great. Massage heat/cool seats are surprising useful. Pre-'016, Off road package is another rare one. I think it was also a special order. Haven't tried it yet, beyond the sport setting.

This is a heavy rig, and without the sports setting and adaptive suspension aides, you will wish you had them. And again, if you live in the northern climes, winter tires and wheel package should be considered.

Good luck with your decision.

Thanks for the info!! Much appreciated!