Mainly NAV but so many other features depend on it like parking sensors, the autonomous driving sensors...etc. kind of feel like buying such a technologically advanced car and skipping the tech package doesn't work for me personally. Just a preference though.
+1 on Tech package: in fact, I truly think it's a little silly that on a car so advanced as this that the Tech package is a separate option. I know some order without, but I think the last unofficial survey it was <5% don't get tech. Even if you're just protecting future resale, it's probably a good idea.
I vote S85D, in my truly biased opinion (see signature below). If you're going to be getting supercharging added for $2k, it closes the gap between S60D + Tech and S85D + Tech to $8k. The X is likely to be more $ as well.
I was originally getting S85 and now S85D, and spent a lot of time running the scenarios. The 85 models with SC included, increased range, battery and motor warranty (also nice for resale) seem to hit the sweet spot value-wise to me. No one's money is unlimited, but in this range of car prices, I wanted to make sure I was maximizing my return on investment.
When buying tech products, I try to get the max value before the "diminishing returns" kick in. For me that was S85. P85, +, D are awesome, but you pay a ton extra money for the extra gogo juice. If money was no object, different decisions can be made. But most bang for your buck? S85 +/- D.