Im super satisfied with 3D MAXpider Kagu Floor Mats Custom Fit. Theyre way classier than WeatherTech FloorLiner kits and honestly less slippery than my old TuxMat Custom Floor Mats tho...

> I have about 800 bucks to spend on protection like floor mats or seat covers Ive owned a few Navigators and floor protection is only part of the mess. For seats, I tried Lusso Gear Car Seat Protector for Leather Seats but they shifted too much on the smooth leather. Switched to Diono Ultra Mat Car Seat Protector with Organizers because the rubber backing stays put better. It prevents those nasty permanent car seat indents which basically ruins your resale value...

Unfortunately, most custom fits for the L model are just stretched versions of the standard Navigator mats and the tolerances are garbage. I had issues with the edges lifting after a few months of use... basically ruined the premium look. I eventually gave up on the plastic stuff and went for Lloyd Mats Luxe Custom Fit Floor Mats. The 48 oz pile weight is double what most OEMs use, so it actually dampens road noise too. Heres a couple tips for the L specifically:

• Skip the universal seat protectors and grab the Canvasback Custom Cargo Liner for the rear. It is a specialized poly-blend that stays velcroed to the carpet so it doesnt bunch up when you slide the power seats.
• Use Prince Lionheart Two-Stage Seatsaver under the kids boosters. The high-density foam doesnt compress like the thin rubber ones do, which is key for keeping the leather from stretching permanently. The weight of the mat is everything in a cabin this big. If the backing is cheap, theyre gonna slide no matter what the marketing says. Honestly, anything under a certain weight spec is just gonna be a trip hazard for the kids.

Man I wish I found this thread sooner. Would have saved me so much hassle.