Played It, Loved It
I ran City of the Spider Queen starting in 2002 thru 2003 in a weekly campaign running around 3.5 hours a game. My players and I both throroughly enjoyed the module, but it is a major undertaking... this module is huge. The party will spend most of many months of gaming far, far away from anyone even remotely friendly. Healers are a must. My players had a cohort cleric who carried every healing spell he could muster every single night. A couple of characters got killed, which makes the DM come up with a plausible reason to add characters in such a remote location. Plan ahead!
Some resources were not available when we played through, and now it would be a completely different experience. I'd highly recommend getting the Forgotten Realms Underdark book. Green Ronin's Plot & Poison will let you customize all the numerous drow you'll run into. The new Races of Stone has good supplemental material as well. With all the twists and turns of underground adventuring, I would highly recommend using Tact-Tiles for your map. We used the old-style Battlemat, but it took a lot of erasing and repositioning. I'd have given a kingdom for Tact-Tiles at the time.
Some other items that would have been fun to have would be: Goodman Games' Complete Guide to Beholders, Blue Devil Games' Poisoncraft, and Silverthorne Games' Template Troves Volume II.
One of these days I'll run this module for another gaming group. I simply loved the adventure. I noticed a lot of errors in the stat blocks of the NPCs, but I ran the adventure starting with 13th-level characters (instead of the recommended 10), so I had to re-write them all anyway. You may consider implementing the magic item Craft Point method of item creation from Unearthed Arcana because your PCs are not going to get to do any shopping.
Charles Plemons