Code:

(defun GetLayoutList (/ Layouts@)
  (vlax-map-collection (vla-get-layouts (vla-get-activedocument (vlax-get-acad-object))) 
    '(lambda (x) (setq Layouts@ (cons 'x Layouts@)))
  );vlax-map-collection
  (setq Layouts@ (vl-sort Layouts@ '(lambda (x y) (< (vla-get-taborder x) (vla-get-taborder y)))))
  (vl-remove "Model" (mapcar '(lambda (x) (vla-get-name x)) Layouts@))
)

Quote:

I have recently revised PlotDwgs to be easier to customize by other AutoCAD users and AutoCAD departments.
This version utilizes two global lists, which are located at the top of the PlotDwgs.lsp file. The lists are easy to edit,
even by a non-programmer. PlotDwgs doesn't use or require previous page setups, or layout plotter configuration
settings. This makes it ideal for batch plotting a folder of customer drawings or other engineering firms' drawings. In
the main dialog, by selecting "Varies" for the paper size, the program determines the correct paper size
and corresponding plotter to use for each layout. This version also includes the option of plotting all open drawings. 
 
  
In order to make this version work for most global AutoCAD departments, a few company specific functions were
removed, such as a plot stamp function for title blocks, and a Bill of Material utility which updates an Excel
spreadsheet for the database. The program may be customized to meet your requirements, such as turning on or
off certain layers when plotting. For the International AutoCAD users that use metric page sizes, search and replace
A-Size through D-Size with your page size names, and also edit the PaperSize function, and change the values of
the Widest~ variables accordingly. PlotDwgs is designed to work with AutoCAD 2000 and up. 
  
These files can be downloaded from: 
http://web2.airmail.net/terrycad/AutoLISP-Code.htm

Code:

;-------------------------------------------------------------------------------
; GetLayoutList - Returns a list of layouts in the drawing in tab order
;-------------------------------------------------------------------------------
(defun GetLayoutList (/ Layouts@)
  (vlax-map-collection (vla-get-layouts (vla-get-activedocument (vlax-get-acad-object)))
    '(lambda (x) (setq Layouts@ (cons x Layouts@)))
  );vlax-map-collection
  (setq Layouts@ (vl-sort Layouts@ '(lambda (x y) (< (vla-get-taborder x) (vla-get-taborder y)))))
  (vl-remove "Model" (mapcar '(lambda (x) (vla-get-name x)) Layouts@))
);defun GetLayoutList