Even if you have a shorter time horizon, you will forgo significant savings opportunities by cashing out your TSP. For example, if you are 45, your $20,000 will grow to $53,855 in 17 years. Keep in mind that even if you really need the money, you may be better off borrowing from your TSP account.
Here, in NYS, rubber floor mats take a real beating during the winter. I use Hi-Temp tire cleaner (amazing stuff) and a brush to scrub the rubber, a procedure very similar to yours. Dressing-wise, I apply whatever looks good at the time, though, I've been really liking Tropi-Care's White Pearl as of late.
Pet dander, dust, and other allergens can settle into the cloth fabric, while with leather you can fully vacuum the seats or wipe them clean. Of course, even cars with leather seats have carpeted floors, which also harbor allergens. So leather upholstery can only reduce allergens in the car, not prevent them.