I do tend to use more minions than specified in the DMG, as per Mearls' comments in one of the podcasts; I find that about 6 per "normal" monster is about right. In this case, I took a lesson from Jeff Quick's old d20 minigame "Hijinx" and let player-described objects be key in the conflict. It was fun, although it broke my mind a little bit to keep coming up with more and more aggressive junk to act as minions.
The sentient history book (reawakened by the evil ritual recently performed by Alene two floors overhead) was effectively a non-enemy; with only 1 hp, you just had to figure out it was there and then find it. Meanwhile, the minions and animated objects were beating on you as you made standard action skill checks. The wizard's spirit (Nithigol the Animate) claimed to be the apprentice of someone known as Inquisitor Zacris, Zacris the Undying. He was sort of peeved when the group suggested that Zacris was, in fact, very dead. Given that Nithigol was surprised that no one was a wizard, it's likely that this tower hasn't always been populated by the Grey Guard.
A few magic items were found in all that mess; a restful bedroll, some dwarven stonemeal biscuits that taste awful but never go bad, a blessed book (containing an old diary) and eternal chalk. I like quirky low-power items that aren't combat oriented. In addition, Temigent found and claimed a black marble egg that contained a fawning, servile shade who would act as his servant. Based on the Prison of Salzacas in AV2, I don't think anyone was sorry that a NPC claimed it; the shade was useful but really annoying in personality! (And ridiculously fun to roleplay. Sniff. I'll miss him.)
The group was really irked to let Scrax the kenku assassin go. They could have killed or tortured him, although it would have been illegal under Imperial law. Scrax's certainty that he would be treated with gentility once he renounced Bramble as his assassination "client" was unexpected by the group. Clearly, not your normal sort of assassin.
We pick up in a month with the group heading south to Halfhammer, to learn a ritual that will be able to prove whether the missing Grey Guard member Caducity Skirr is dead or missing. On the way they've been told to stop by the halfling town of Mudtunnel. Built inside an elemental anomaly, a whirling tube of elemental muck that scares away most natural predators, it's a fairly safe place -- except two of the three Grey Guard members there have recently been slain, and the one remaining member has no idea why.