Similar here. I have a spreadsheet I started with all the characters from one "world" (over 100 and I don't have them all entered) along with a document containing details of settings and such. Doesn't really work as well as I had hoped.
Downside of a wiki is that it's online which means it's accessible only if you're online and I just know that I would want to work on things when the power or Internet is out. Granted, power and Internet only go down rarely, but it seems one or the other goes down right when you need something.
If you had a private wiki hosted on your own private server, that might be more workable. With battery backup, you'd still have access in the event of a power outage. But you'd need your own server and all that.
I've seen suggestions of using mind-mapping software and I've tried that but, ugh. For me, mind-maps are cumbersome and stupid. I know some people swear by them but for me I just think they're stupid.
I think the best bet is probably a relational database with a nifty front-end. Wouldn't be hard to build, but it's one of those things I haven't gotten around to doing. I've looked at options like FileMaker and some others, but the easiest way is probably just MySQL (or one of the various alternatives) and PHP. Put it on your own server, use battery backup and there you go. Of course, in your case, that would require the dreaded coding which I surmise you don't want to do.
I know there was, if I remember right and I don't guarantee that, an open source (or cheap) wiki software that wasn't hard to install. It seems to me I tried it once on a test website. Or maybe I didn't. Who can remember? Not me, apparently. I cannot recall the name either. Oh, wait. Never mind. It used to be called Piwik and it was for WordPress analytics. No wonder they changed the name.
TL;DR: Um, I guess I got nuthin'.