The high Sierra in California in September is where all good backpackers go when they die. The bugs and people are gone. Nights are chilly and days are usually perfect for hiking. I've gone only to the steep east side and have entered via five different passes, at least. There are far fewer people on the east side, and in many places, after the first day, you can just pick a destination on your topo and head off cross country. You're unlikely to see a soul all week. There are thousands of lakes, plenty of crystal streams, endless white rock mixed with some darker volcanics. Elevations are high with passes at over 10,000 feet. The John Muir Trail passes this region as well as the very challenging Sierra High Route, but you can make your own route. I am sorry that Weebly strips photos so badly.