Trillian is pretty nice. I used to use it pretty frequently a few years ago, and like Digsby, it lets you set up multiple clients such as AIM.
I haven't really ever taken much of a technical look at it, though. I assume that logging and chat histories are synonymous; in that case, I was able to look up contacts and quickly get text documents for conversations between now and 2009, so I would think that logging support is at least decent. I can't say much on different icons per account, unfortunately.
The software occasionally pulls some light spam-oriented messages, such as recommendations to upgrade to the full version. I don't recall it ever getting so out of hand that I wanted to uninstall it. I believe Digsby would be a bit more ridiculous in this area.
The
current version takes less up than 30 MB of space and isn't very resource-intensive.