First I want to make sure I understood your desires correctly Dark Serph. You want:
- A setting with lots of published materials to provide campaign depth
- A setting in which magic plays a part, but high powered magics (iow 7th + level spells, magical creations, epic level NPC casters running around, etc) are not common.
- A setting with a unique feel.
Is all that correct? If so then...
The IK setting is very rich in detail and for the most part can serve very well. It is, however, steampunk-ish (the over all tech level is higher than traditional fantasy, and while not neccesarilly steampunk lots of the illustrations and PC gear make it feel that way- they call it "Full Metal Fantasy") so may not be what you want. Persoanlly I have found some problems with a bit of the setting specific rules and classes. I found the gunmage disappointing, and would recommend homebrewing a better version. The item creation rules are fairly complex as well and less than satisfying. However, if you steer clear of those things I have to say that I find it one of the most facinating campaign worlds available. There are lots of minis (via the Warmachine Minis wargame), a regular magazine called No Quarter, and a good fan base. The Monsternomicon is the best monster manual ever, and a sequel is coming out. The Witchfire Trilogy, the introductory adventure is quite railroady, however, and is another one of my frustrations with the setting. What it boils down to is the setting provides excelent fluff but a wide range of crunch ranging from wonderful to poor. You could, however buy the campaign setting book and run it in whatever system you like and do just fine for the most part.
Freeport is a great and well detailed city and could serve as a minicampaign setting. No real need to make it a piratical type game, just an urban one in a port city. Lots of supplements for it both in print and pdf.
Now this might seem a bit odd, but World of Warcraft RPG offers a well detailed setting with a magic level similar to the core books. Lots of well done supplements for that too. I have never played the MMORPG (but was always a fan of the RTS series) and found it very nice. Just be careful about checking to see which edition books are for if you go picking up several.
I have heard lots of good things about Kalamar and while I dont own the core book I do have a few of the supplements that I have used for others settings. It is well done and certainly on par with FR or Midnight in my opinion.
I am also among those who would suggest that Eberron is Common Magic not High Magic, however it can have a "feel" similar to that of high magic, in that magic is a common part of everyday life. There are lots of preview materials over at WotC's site so you might want to look over them first.