I wouldn't say I know enough about assembly to offer suggestions however,

I bought "PIC'n up the pace" from Square1 before I knew there was even more then one programming language for PIC's. The books seems like a excellent book for learning assy. I hardly know anything about programming micro's and I could almost understand some of the syntax that are taught.

http://www.sq-1.com/

I imagine the prerequisite for this book "Easy PIC'n" would have been a better choice for me, but I found this one at a half priced book store so I couldn't really pass it up.
I look forward to the day I can move onto learning assembly though.

Good luck!!