I found a great pljoin lisp.... I searched around a bit and found that other people were having trouble with their pljoin lisp file. Most people didn't the extra steps to join plines using the PEDIT command. AutoDesk got rid of the PLJOIN command a long time ago when the invented the "fuzz" factor. The attached pljoinfuzz lisp is similar to the pljoin lisp, just has the fuzz factor added in. Try it and love it like I do!!!
Side note, I'm on Acad Architecture 2010.