I bought a set of sagged bags for my Standard and used them for two years before getting a new set. The bike was totaled after 2 weeks of using the new bags, so I don't know how they would have held up, but I recommend using a high quality leather conditioner (I used Obenauf's heavy duty lp
http://www.obenaufs.com/lp.php?osCsid=dbf0d918a88c54552a66125d8d4266b0) and seriously considering leather lid's support system (
http://www.leatherlidinserts.com/). You could also make your own inserts if you wanted.
I had done both for my new bags and figured they would last about as long as the Valk. I now have an Interstate and the OEM hard bags. The OEM leather bags look great on the Standard (assuming they haven't sagged), but are a PITA to open and close because of the three buckles on each bag.
Here's the Standard with new bags this past spring just before the accident:

And here's what she looked like with the saggy bags:
