Schoolhouse Tunic Sew-Along

Have you heard about the Sew Liberated Schoolhouse Tunic Sew-Along that Rebecca from Sew Festive Handmade is hosting?  I think I'm going to join.  The only pair of clothing I've ever made is the pajama pants for Mr. T I mentioned the other week. (I've finished them.  I'm just not ready to post the final product.  It's coming soon, though).  And while they're pretty awesome and he loves them, they're not exactly neat or refined.  I want to learn how to make something I can wear in public, and maybe even how to do a french seam!  So, I'm going to take the plunge and do it...

I'm going to go with the dress version.  I think if I can find a good, relatively neutral fabric I'll be able to wear it to work this fall/winter.  Also, I just know I would never wear the shirt no matter what fabric I used, and I don't think I'd wear the tunic with jeans, so hopefully I can find something that works with tights and boots...

Here's the question - what kind of fabric do I use?  Rebecca dedicated a whole post today to fabric selection, but unfortunately it's not really answering any of my questions.  I did look through the Art Gallery she recommended, but all the prints are too busy for me.  I'm thinking of going to JoAnn tomorrow to look around, but I'm worried the quality won't be good...

Any opinions or suggestions for a first time clothes maker?

Thanks!