I really love Bridget. It fits what you're looking for.
Sadie, Sierra, and Cora fit the image you want perfectly. Molly and Hannah/Anna/Annie also came to mind.
Love Cecily for your image! Antonia also comes to mind.
My favorites (ranked in order of how much I like them):
1. Cora (really makes me think of a beautiful 'rodeo queen')
Lukewarm for me:
Maisy or Macy
Those are all good names. I like Cecily, Celeste, and Sadie the best. I was going to suggest Lacey until I noticed your name was Stacy, lol. I wouldn't use Macy if I were you.
Cecily and Cora seem like the best fit in my opinion. =]
Chanel - has the same cheap feel to me as Porscha, Destiny, Mercedes, etc
Nadine - not bad, just no wow factor and nothing really "pretty" about it to me
Suzette - just makes me think of Suzanne and Suzy which makes me think of my mid-40 year old Auntie. Susanna is lovely though
Priya - don't hate it just don't love it. I prefer other P names like Paloma, Penny, Penelope etc
Dawn - I just find the sound a little harsh personally
Kiera - how are you pronouncing it? I don't hate this either but it is strongly associated with an actress I'm not that fond of and I find there are a few similar names with different spellings, and a couple of ways to pronounce it, (Ciara, Kira, Kyra, Sierra etc~) so it confuses me a little
Personally I think Cecily/Celeste, Noelle & Evelyn would make beautiful sister names. I love these names especially the beautiful Cecily which is a fave of mine too. Sadie & Gwen are really cute together too in a less frilly way :)
I love the 'wearing a dress playing in the mud' imagery! From your list I like: Celeste, Corrina, Noelle and Cora. I also don't mind Nadine, Sadie, and Dawn but the rest aren't really my style.
My suggestions of pretty but strong girls: Hope, Phoebe, Julia, Claire, Kendra, Zooey, Charlotte, Leah, Piper, Ivy, Audrey, Amelia, Skye, Sage, Grace.
From your list I love Gwen, Cora and Sadie. These names are cute but also spunky, which fits wearing a dress playing in the mud imagery (great describtion btw). I think Eve or Eva would fit this description better than Evelyn which is while nice seems a little fussy.
I've been thinking about Julie a little. But I'm not sure. It feels incomplete, but Juliana/Julian doesn't really do it for me.
Kiera i am pronouncing as Keer-ah There is a Character on the tv show Reba named Kiera that I just adored. I'd love to put Penny on my list. But we watch the big bang theory and DH can't get past that association. lol