Most hotels won't have any info for DragonCon 2014 yet. The earliest of the host and overflow hotels (ie, the ones with the convention rate that will be posted to dragoncon.org once DragonCon 2013 is over) usually don't start taking reservations for the next year until the week of con this year. I think the Sheraton opened their reservations up for DC 2013 a week or two before DC 2012, if I remember correctly, but the others all typically open up during or shortly after the con. The Hyatt and the Marriott have typically not opened their room block at all until a specific date and time in late September to mid October, and usually sell out completely within the first 15 minutes. The main LiveJournal community will have all the info about booking for 2014 starting around mid September 2013: http://dragoncon.livejournal.com/
This will be my fifth DragonCon, and I've always stayed at the Hyatt, in the Radius Tower (which doesn't have the elevator problems that plagues the rest of the Hyatt, as well as the Marriott). For 2013, the con rate for a double occupancy room was $217 per night, and I think the other four host hotels (Westin, Marriott, Hilton, Sheraton) are in a similar range. There are overflow hotels with lower rates, but you won't get DragonConTV. The con rate goes up a few dollars per night every year, but I wouldn't expect it to jump dramatically.
My husband and I fly in from southern California, and since Atlanta is a hub for a major airline, it's pretty easy to find non-stop flights. From the airport, we take MARTA, which is cheap and direct and (I've heard) faster than taking a cab in traffic. The end of the line stop is basically in the Atlanta airport, right next to baggage claim, and from there all trains only go one direction, and they all stop at Peachtree Center, which is directly beside the Hyatt, Marriott, and Westin host hotels, and just a short walk from the Hilton, Sheraton, and various overflow hotels. It's a couple of dollars for a round-trip fare, no transfers, very easy to use.
Best advice I can give for booking for next year is to join the DragonCon LiveJournal and keep a very close eye on it once the posts about 2013 have calmed down. They'll post the info there on when the various host hotels are opening their reservations, and have links to rate info for all the host and overflow hotels. Book as early as you can, and if you want to get a room at the Hyatt or Marriott, set your alarm for the day the room system will go live, and make sure you're at your computer with all the info you need (how many nights you're staying, dates, names, addresses, credit card, etc) at least 5 minutes before reservations open up, then when the site goes live go straight for the room type you want, paste in all your information, and get through as quickly as possible. The Hyatt and Marriott landrushes are notoriously bad, typically crash the reservation servers, will time out in the middle of you trying to book, and sell out in 15 minutes flat. If the Hyatt or Marriott aren't your first choices, I recommend avoiding the insanity and booking with far less stress at the Westin, Sheraton, or Hilton, or any of the overflow hotels. Things do tend to sell out early -- just not quite this early.