I'm ready to purchase a Model S. I've been doing lots of research, but wanted to see what you all think are the most important upgrades/options. I definitely want the glass/pano/sunroof, but undecided on everything else. Also, would you recommend a 2013 with lower miles or a 2014 or 15 with higher miles? I live in the foothills sw of Denver. This will be our 3rd car (we have a 4WD SUV & 4WD pickup), so it'll be our "run-around" car. Thanks!