just a few things i reckon would be advantageous.
1.buff expiration time (staying online a few more minutes waiting to apply next buff instead of logging off and it running out within minutes)
2.variable camp time on geologists (only really beneficial for stone and marble but at least you can set it to look for these if your going offline, or if you have been away a few days and need to catch up, working out when a mine runs out is upto the player)
3.stackable treasure hunts for explorer (good for if your going away for a few days)
4.trade filtering
5.trade slots (make branch office upgradable granting 2 extra slots per level)