Don't you have to be near the Item Familiar to use it?
Personally, I'm a fan of Dwarvencraft Blue Ice Gnomish Quickrazors as Item Familiars. That's partly because I like playing Factotums and the weapon is great for that, but also because you Sleight of Hand the weapon back into your sleeve with every attack, so it can only be targetting mid attack (if you see a close opponent holding an action, he might be planning to sunder it... so step back and shoot him). Blue Ice assures that spells like Repel Wood and the like won't matter... there's spells to target stone, metal, and wood, but none that target ice, and Blue Ice doesn't melt. And once you cast Augment Object or Hardness on it, sundering the weapon becomes an exercise in futility.
I do REALLY like having a portal to your stronghold inside a portable hole though. Being able to retreat into your stronghold whenever you need is just so very handy. Spend some of that Landlord money on spell turrets that spam heals and buffs, leave reserve troops back there, and so on. Also, building a castle is just fun. I personally prefer taking over some rediculous castle the DM has created and using that. They usually have all kinds of implanted magic that you're not allowed to steal... so once you take it over, you have things like indestructable doors and crazy teleporters and such. That'll teach the DM to use fiat when building his dungeons!
JaronK