Mmm... when I first really started playing Vicky, I remember *always* going liberal, and turning every monarchy into a Democracy as soon as the plurality was high enough. Around this time, I randomly decided to go against my norm and played a game as Russia in which I tried my absolutely damnedest to avoid changing government, or to switch ruling parties. While I feel like I was less productive with my nation that I could have otherwise been, it was a *great* deal more fun dealing with all the Russian revolts and unrest. Since this time, I never fret when I have a conservative party in power.
I guess I usually like to play to a countries historical leanings. USA can go whatever direction they please, but usually end up with Republican's holding office from 1860 until 1936. Russia and the Ottomans are just the opposite: sticking to their conservative absolute monarchies for as long as possible until an overthrow is imminent or I find some historical date for implementing a Con Mon.