Women's Dress Shops

I spent the weekend surfing the web looking for a good shop to buy chic dresses suitable for women in the 40's size 10-12. I started out and I literally just a dress in my closet. I do not spend a fortune, but we want to look nice (not slutty, or age appropriate :-)). My style is heading scattered brown polka dress worn by Julia Roberts in the race track in the movie Pretty Woman.

Any help would be appreciated.

Live in Michigan, so advice on traditional stores would be nice as well.

Thank you very much

you can try Lane Bryant. Im not sure how their sizes go but my mother shopped for years and it is generally very satisfied with their orders.