Maybe the guild hall could add an element whereby your RPs increase with the number of challenges your guild wins. The rate would depend on how much it is upgraded.
Also for auction house: maybe it could act like the sports shop whereby you get a discount on players you buy and a little bump on players you sell. The % would increase as you upgrade.
Finance building. There has to be more that can be done there, it's absolutey rubbish for how much it costs. Perhaps if you are a good player, then you get approached by decent sponsers who increase morale slightly on your best players cos they get more in sponsorhip and advertising fees. Not really my best idea, but something would be better than it is now surely?