I wouldn't sit on neopreme seat covers if they were given to me. First, neopreme is not (contrary to what some ads say) waterproof. It will soak up rain or moisture like a sponge if it's not wiped up quickly enough, and then it takes quite a while for it to dry out again. Why do you think Wet Okoles are called Wet Okoles? Okole is Hawaiian for "butt".
Then when they have a colored nylon cover, the color fades quickly and unevenly... so with much sun exposure, they start looking bad too soon. Finally, the cheaper covers like are sold by Smittybilt (imported from China) use inferior/thinner neopreme that will start stretching and looking bad before you know it.
Neopreme seat covers sound great in the ads and they look great when brand-new but their severa; significant downsides far outweigh their initial good looks.