Am in the midst of a run. Used statehouses strategically (particularly on paper) early on. Low dev provinces firmly in territory mode -- swapped a lot of Persia out of states once I had better land in India. I was using vassals to spread costs between Admin and Diplo, so didn't use vassals to hold onto Persia for me.
Trade companies I have been sparing with, they are there to boost my trade share primarily. I used the boost governing capacity thing from governing reforms several times while also unlocking reforms (no need to rush to absolutism related reforms pre 1610). Am split between trade companies (for weak-ish but tradepower bonus areas), territory (for chaff), and states (for better areas) in my non-Indian clay (Burma, Gulf of Aden, Malacca, China).
Once I was swimming in money from trade, taxes and production from a mostly unified India (plus Persia) I gave everywhere a statehouse.
Going to drop L'etat c'est moi and its Admin capacity for the regional representation now I have enough for statehouses everywhere, economic hegemony, and the expansion finisher as there is going to be pretty much only territories soon.