I agree that Tiana should get some attention, but I am at a loss as to what attraction that franchise would best lend itself to. On the subject of Aurora; Maleficent is going to get a movie, so perhaps we'll see something of her if the movie is successful.
ORDDU: The original Maleficent is successful enough in her own right and really doesn't need another movie as an excuse to promote her further. She's actually already featured in a stage show called Dream Along with Mickey. From what my sisters and I have heard, she's too frightening for little ducklings to be able to deal with and that's why you only see her out for meetings and greetings on rare occasions.
The whole Maleficent movie is supposed to be about how she got to be so evil...hmm...Wicked?
Tiana does not sell. Take a look at merchandise at retailers and you will see. Economics 101.
ORDDU: Also, Tiana doesn't really fit the time period for Fantasyland since her story takes place in a more modern setting than all the other princesses stories do. Therefore representing her at the parks is quite a challenge. I do believe she will at least be included for meet and greets inside the Princess Fairytale Hall.
ORWEN: Besides that, Tiana doesn't have any iconic buildings in her story that would stand out like Rapunzel's tower or Cinderella's Castlet, etc.
The tower from Tangled was also a pretty good example of standout architecture from the movie. There's really no thematic architecture that stands out in Princess and the Frog, except maybe a river boat, which they already have. Also, we can point out a lot of characters through Disney history that aren't represented in the theme parks at all.
ORGOCH: Man, ain't that the truth--startin' with us Cauldron gals! But I blame my two looney sisters fer that. They both went an' ruined Black Cauldron ta the point where nobody cares fer us!!!
My two cents on why Tiana is not prominent in the parks:
1)As others have posted, Princess and the Frog is tough to design areas around. The film, while beautiful, only has a few standout buildings that Imagineers can bring to the parks. The most notable is Tiana's restaurant.
2) Princess and the Frog, while popular with fans, seems to not be as popular to the general public as Tangled is. It earned nowhere near the box office revenues Tangled did, and, in Disney's eyes, is less marketable to little girls than Tangled. Plain and simple.