The abaya trend right now has been all about the butterfly and bisht styles, which often don't have defined t-shape arms, and we all know milhafa style overhead abayaat don't do too well with a coat. For those of us that don't live somewhere warm, coats are necessary since abayaat fabrics tend to be lighter (and if they are not we die indoors anyways). My solution in the past has been too wear a tonne of sweaters underneath or don't them at all when it's cold of wet out. Well, if you can find or sew yourself a good updated version of the 1920s cocoon coat, you have the perfect coat to layer on overtop of the wider fuller cut abayaat. Burberry was selling some practical and mod takes on the cocoon coat but they were out of my budget so I got a pattern like this one http://www.fabric.com/notions-patterns-sewing-patterns-by-category-coat-jacket-patterns-macphee-workshop-cocoon-coat-pattern.aspx. and this one http://www.voguefabricsstore.com/store/catalog/Patterns-Folkwear-260-Sunburst-Cocoon-Coat-p-1695.html. I'd love a cocoon coat made in a light weight denim. There also some pretty light weight cocoon sweaters floating around, perfect for layering. So in the winter I will wrap myself up in a little warm cocoon coat, and in the spring emerge a beautiful butterfly. Also, cape coats are good combo for outdoors excursions for those butterflies that don't like to go into hibernation.
And here are some links for cape coat patterns http://www.voguepatterns.com/item/F1405.htm?search=cape&page=1 and http://www.voguepatterns.com/item/F9653.htm?search=cape&page=1.