I did this using a Nikon Coolscan 4000ED for my own stuff years back, and am currently using that same slide scanner at a historical society where I hav scanned upwards of 2K slides to date.

The VueScan scanning software for this unit is pretty good (actually, better than just "pretty good") - it does an excellent job of cleaning up scratches, faded colors and dust spots (plus red eye in many cases) - with the accessory slide feeder to auto-feed the slides it is also pretty automatic (though you'll want to keep an eye on it - if the slide mounts are bent at all they could jam - nothing difficult to fix but it just means time wasted if you leave it alone for 30 minutes and return to find only 2 slides scanned before it got stuck).

Flatbed scanners are okay, but a dedicated slide/negative scanner might prove to be an infinitely more efficient use of your time.