I'd say either senate then the resources (stone - wood - silver in that order)
although getting academy to lvl 10 or 13 is also a "must" do the discount on cost (lvl 10) and time (lvl 13)
if you have the money to spend you can gold that too, but it usually goes pretty quickly
which is why I suggest removing shared reservations.
if people still want to hug let them, but it will be funny to see them get mad at each other for killing each other's cs