Hey there, sorry for the late response, but here are a couple things that may (or may not) catch your eye for D&D:
Chessex dice booth. I know I already have more dice than I need, and I STILL buy more from their booth. Also, Chessex has great battle mats. Often they bring their "factory seconds" which are cheaper, and to be honest, the smudges are minimal...totally worth looking into if you play D&D with minis.
There are vendors that sell loose D&D minis, so you may want to see if you find a few to fit your current campaign.
Hirst Arts: If you have any interest in terrain for your games, you should swing by this booth. He sells molds used to build your own gaming structures. It's like Legos for gamers. If you like the concept, but not the work, Dwarven Forge sells finished terrain (with prices to match though). Additionally, I don't know if Fat Dragon is still around, but they sold CD's of printable terrain that you assembled. Again, depends on your time/skills/preference.
Maps & dice towers...don't know...various vendors that carry these come and go. Paizo does have some nice maps, I think they even have laminated maps that work with dry erase markers. Stop by their booth and check out what they have. While the Paizo maps are beautiful, I prefer the Chessex battle maps as they are more generic and hence I find are more useful.
Map systems and special deals tend to be more subjective. Over the decades, I've found what works for me. A "deal" on a system or game gimmick that I won't use is not really a "deal."
I just went back and read that this will be your first Gen Con. If you're looking for D&D gaming supplies, you're in for a treat. Go check out the Exhibit Hall. I challenge you to see it all in one day, HA! Seriously, there'll be plenty to see and lots of goodies to bring back to your D&D game. Bring a large shopping bag (or 5). Have a great time and enjoy your first Gen Con!