yay, a fellow XFCE user
some have been mentioned before maybe, but I'm installing:
policykit-1 (fixes logout),
some drivers,
Synaptic (not for upgrade),
xfce4-powermanager,
xscreensaver,
laptopmode-tools,
chromium,
pidgin,
gimp (2.8 from Experimental),
scite (my favorite text editor)
some games, too:
pysolfc,
crawl-tiles,
assaultcube,
dopewars,
numptyphysics,
dreamchess
(I'm more of a casual gamer)
actually I'm installing and trying out a lot of stuff all the time, but this is more or less what I ALWAYS install on a new system