The best place for young adults would have to Memphis, Tennessee. It's the biggest city in Tennessee with 1,305,946. It has anything that a young adult would need to live a happy, fun and adventurous lifestyle.
A lot of young adults live here. You'll have no problem fitting in. You'll also never get bored in Memphis! It's an amazing city.
In Memphis there are a lot of jobs. Many fortune 500 companies are headquartered in Memphis so you won't have trouble finding a job. Here's a list of some well known work places in Memphis: Medtronic Sofamor Danek, First Tennessee National Corporation, Pinnacle Airlines, Inc., Thomas and Betts Corporation, Mueller Industries, Fred's Inc., Verso Paper, Allenberg Cotton Co., Dunavant Enterprises, Accredo Health Group, Inc., GE Capital Aviation Services, Inc., Baptist Memorial Hospital, Methodist LeBonheur Healthcare, Baker Donelson.
There are a lot of night clubs in Memphis also. I don't know if you like that sort of thing but if you do than this is just another benefit of Memphis. Here are some well known clubs there: Backstreet Night Club, B B King Blues Club, The Daisy, Club 152 on Beale, Hi-Tone, Hollywood Disco and Gold Club.
The weather in Memphis also varied. You get all 4 seasons. Memphis has a humid subtropical climate, with four distinct seasons. Winter weather comes from the upper Great Plains or from the Gulf of Mexico, leading to drastic swings. Summer weather may come from Texas (very hot and dry) or the Gulf (hot and humid). July has an average high and low of 92.1 °F (33.4 °C) and 72.9 °F (22.7 °C), with high levels of humidity due to moisture encroaching from the Gulf of Mexico. Afternoon and evening thunderstorms are frequent during some summers, but usually brief, lasting no longer than an hour. Early autumn is pleasantly drier and mild, but can be hot until late October. Late autumn is rainy and cooler; precipitation peaks again in November and December. Winters are mild to chilly, with average January high and low temperatures of 48.6 °F (9.2 °C) and 31.3 °F (−0.4 °C). Snow occurs sporadically in winter, with an average yearly snowfall of 4.6 inches (120 mm). Ice storms are a bigger danger, pulling tree limbs down on power lines.
There are also a lot of monuments and places of interest in Memphis: Here;s a link to some attractions: http://www.memphistravel.com/attractions
Ultimately, Memphis is a very good place for young adults. I hope you don't stress too much on your decision of where to move to in Tennessee. I hope I helped. If you have any questions feel free to message me.