Since mstevens OP listed "Free" as the 1st feature desired, I'd like to suggest GS Finder Plus. GSF+ has tons of options for configuring it to whatever works for you. You can even set it to always default to root or to last file/folder. However, it does not support FTP, which I'm guessing is what OP lists as "network shares?" Small footprint, very powerful - worth a try. More info and download link here:
http://tinyurl.com/62eshh