Ok, I'll try to give as much info as I can in a short amount.
Dragoncon has been going on for 30 years. Last year was the 30th aniversary. It originally started in 1 hotel, it has grown to be such a huge event it is now held at 5 hotels and at america's mart. The five hotels are Marriott, Hyatt, Hilton, Westin, and the Sheraton. Each hotel has different things going on in all of them. The panel line waits are that much shorter due to the fact at how quickly they clear out the rooms. Dragoncon was created by the fans for the fans. So at times it may not have super huge celebs like comiccon, but the people are unlike any other con. Most cons you go to you might talk to someone here or there. When you talk to people at Dragoncon there more like family, it's hard to explain. I attended my first DC 2013, after that I was hooked. This year will be my 5th year in a row attending. I first attended just because I saw one video and I was like I have to go to this. Also the major difference with DC is that it' Starts on Friday (a lot of us get there wed & thurs) (now there starting things on Thurs) and it doesn't really shut down till Monday at 5pm. The reason it never really shuts down is due to being held in the hotels, so they don't need to clear convention halls and such. With that said, this is also the reason a lot (most) of the people at DC are drinking (alcohol). Also DC is more of an adult event, most ages you see are 21-70. Yes you do see younger people mostly Sat due to the Parade. They have a parade, it's the largest in Atlanta, and 2nd largest in GA. The list goes on and on. Some of my closest friends I have meet at Dragoncon. I'm going to post the video that started me going as well as the best advise for attending Dragoncon for the first time. If you have any other questions, feel free to ask, were all here to help.
https://www.youtube.com/watch?v=bbC4XG-L1sE
https://www.youtube.com/watch?v=Ro1S2nhQLf4&t=587s