I love series and stand alones. If I can get the books to read them in order, I will, but I won't let it stop me if I can't. I couldn't even begin to list the series I've read, though some of my favorites are Robyn Carr, Debbie Macomber, Nora Roberts, Stephanie Laurens.
I frequently will go back and get older books in a series so that I can get the back stories on some characters, but it isn't a requirement.