One of the first customizations I make to any new KDE setup is to a) map win+1-0 to switch to desktop N; b) map shift+win+1-0 to move window to desktop N; c) set up 10 virtual desktops. I then run everything full screened and avoid alt-tab. Browser on desktop 1, terminal on 2 (with its own splits), IDE on 3, etc. Over time I found that I could get rid of the panel entirely since I know where all running applications are, and launching applications using krunner is just a win key away. System tray I ended up needing, but I added it as a widget on the desktop itself, and it works well enough there.