I've managed to fix my old laptop (again) and got it working under LXDE, as opposed to the KDE desktop I've been using on Slackware on my usual computer, and I've hit a bit of a snag.
PCManFM is pretty good, but it's lacking a bit for me. On KDE I've been using Konqueror as my file manager/browser because of the great amount of features it has that manages to surpass even Nautilus.
The problem is, Konqueror is very heavy on the system, requiring KDE support to be started, etc, and I want to avoid that.

What I'm actually after is a GTK alternative that doesn't try to manage the desktop without asking (Culprit: Nautilus), has the tabbed browsing and sidebar, and if possible, Konqueror's ability to open some documents in its own tabs or change directly to a terminal view. Those are the key features I want.

I suspect I'm after something that doesn't exist again, but it's nice to get confirmation if possible.

Honestly, perhaps custom compiling nautilus with the options you want in place or alternately compiling Konqueror for the system are probably your best options.

Edit: I've not used them but a coleague suggested giving velocity and thunar a try.

I wasn't aware Nautilus could be compiled with the parts of Konqueror I want.

Compiling Konqueror, on the other hand, still implies that when it's launched, it'll need parts of KDE - something I'm trying to avoid.