We've purchased 2 Model S and 1 Model X.
Our first Tesla was purchased in early 2013 and traded in last summer for our X, after almost 100K miles.
When we purchased our 2012 S P85, Tesla's standard mats were extremely poor quality - so we purchased Tesla's premium carpet mats - which are now included as standard. With our X, we ordered the hard mats for the front, middle and rear seats.
The only other "upgrade" to our S P85 was adding the center console, which is also now standard.
We didn't install any additional window tinting or wrapping. Even in Texas heat, the including tinting, coupled with overheat protection and pre-cooling with the smartphone app has kept the vehicle comfortable when we get in.
Other than the typical door dings, some gravel nicks on the front (which are easily fixed with a little touchup paint), and some curb rash on the rims - the exterior of the vehicle was in fantastic shape. The paint held up extremely well - and we haven't seen any paint issues with our 2017 S 100D or 2018 X 100D.
The one item we would strongly encourage, especially with the ultra white seats - getting something to cover the seats when you have dirty or wet clothes. This has protected the ultra white seats in our 2017 S & 2018 X. Since we only do this occasionally (like after exercising), rather than buying seat covers, we purchased a couple of "bath" size ultra white towels and added some inexpensive snaps to fasten the towels around the headrests. This has protected our white seats from transfers (when wet) or dirt - and the towels can be easily washed if they get dirty.
Would also recommend getting Tesla's tire pump/tire repair kit. Since there isn't a spare tire, if you get a puncture, this could allow you to resume your driving until you can make arrangements for permanent tire repair or replacement.
The other items to consider are additional adapters for the UMC. If you're planning to charge at a home using a dryer outlet, you'll need a 14-30 adapter (or possibly 10-30 for older homes).
