The suggestions about getting Allies to do something specific are welcome, but they really need to improve AI.

Eg 1

My protectorate Italian States joined me in war with Spain. Italian States is bordered by Venice (peace), Liguria (Spain, war, 1 unit), Genoa (peace), and Naples (Spain, war, no units). Italian States have a full stack, but do they do anything with them, say by attacking defenceless South Italy? No, they just sit around watching the grass grow. Their fleet does something, but their army is unable to move anywhere. It is extremely rare for your allies to move even a single unit into neighbouring enemy territory even if they outnumber them by a large margin.

Eg 2

Different game. My protectorate Savoy is, as usual, at war with France. They have a full stack, and decide to all head for France. However, there is a half stack of French troops 3 squares away from the Savoyard (?) capital, and so, unsurprisingly, Savoy is destroyed next turn. Good going guys.

Eg 3

Different game. As Poland I have vacuumed up Prussia, Austria, the Balkans, and half of Russia. I am by far the most powerful and richest country. Denmark, who have lost Norway, declare war on Hannover, my protectorate, so we are at war. They just sit around in Copenhagen, until I burn down their school. The purpose of the war was what exactly?

Same game, about 10 years in UP declare war on my protectorate Courland, despite them not even having a port, and not being at war with any of the UP's allies. Huh?