ChattanCat's site gives the best instructions I've ever seen for fringing the end.

You should gat "So You're Going to Weat the Kilt" and read his instructions on making a belted plaid as well. Making one like that would look--IMHO--must better than just letting it hang down.

Personally, I prefer a great kilt (breachan feileadh) when I want tartan hangin down in back, but then I am something of a throw-back to early man. The breachan feileadh looks like nothing else, and for formal wear, it can't be beaten.