It really depends on the con. At most 'normal' cons many people will dress up in exciting, often skimpy (I have NO idea why, but it's a thing that happens.) and or lavish, things and run a muck. (Mostly on Sat night) Personally, I say be comfortable. The doll people tend to seem a bit on the extravagant side, so packing a nice dress-up outfit may be good too. 'Most' of the girls I know who con fit into one of two categories:
"I'm comfortable and that makes it easier to just relax and have fun."
or
"LOOK AT MY BOOBIES! ... LOOK AT THEM! ...~ah-HEM~ I 'said'...."(you get the picture) and people tend to respond as is presented.

Guys tend to be either very relaxed or full time dress up.

Now that I think of it, it's very much like war weekend at Pennsic down in the bog. If you keep that mindset you should be fine.

Just as a guess I would think that you'll see a lot of people coordinating with their dolls, which may be a fun approach for you as well.

Although I have to say that if you run to the opposite side of the country and then decide to pull out the exciting outfits I will be at the very least a little jealous :-P