While it's up to every group to decide for themselves, I think the entertainment value for your players - if they are experienced players - will definitely be higher if they create their own characters. Fill out the party with one or two DL classic NPCs if required.
Note: creating their "own characters" does not mean, in this context, that they get to create their own backgrounds. Pre-existing relationships with NPCs and others in the the DL world impacts the story and you can work most of that in by not-so-heavy-handed rigging of the behind the scenes plot to make it flow, while still giving the PCs an illusion of control.
If your players are at all familiar with the story or novels, my advice is to change DL1 and parts of DL2 around greatly. There is just too much room for metagaming there. By doing so, you keep the adventures fresh and the element of surprise is preserved.
After that, the modules themselves are much less well known (in the sense the novels did not spoil them) and you should be good-to-go with the usual DM modifications we all do to commercial products we run.
The subject of running a classic DL campaign is a common one on the
www.DragonLanceforums.com boards or our own forums at
www.dladventures.com. Drop by either and pick up some in depth advice.
Sov Press just released the 320 page
War of the Lance hardcover sourcebook at Gencon (out in stores Oct. 1) so there are about to be a whole lot of WotL DragonLance campaigns being started up in the next few months.