I think it's better off to start with the qt versions rather than the wxwidgets versions actually, but anyhow these old bitcoin source codes are not as good looking (in the sense of code readability) as a project like gocoin.
Alright, but just a warning about the Qt builds:
I don't know when they started building with Qt5, but old builds using Qt4 (if any) are going to be extremely hard to compile since most distros stopped shipping Qt4 libraries in their repos. You're better off using an older distribution in that case.
Happened to me while I was trying to run Armory (a bitcoin wallet) so this could be relevant here.