I have some routines that I wrote when I didn't have the Multiple option in the DIST command [attached]. SumDistCont.lsp with its SDC command is similar to DIST with the Multiple option with the added feature that it reports each individual distance along the way, as well as the cumulative total. SumDist.lsp with its SD command does the same reporting and accumulating of a total of multiple distances, but unlike either SDC or DIST / Multiple, for distances that are not strung together continuously, but separate -- it asks for both points for each distance, rather than just the next point and the next, etc., but still adds them up as you keep picking points defining more distances. So you can get the total length of [for instance] a set of Lines representing parallel beams.
EDIT: If you're interested in selecting objects with lengths, rather than picking points to define straight-line-only distances, so that you could include the lengths of Arcs, Splines, etc., there are routines out there to do that. For instance, there are at least three just in the first page of returns in a Search on the Cadalyst CAD Tips site for "total length."
Kent Cooper, AIA