I would agree that there are consistent threads in Russian foreign policy - just like in that of any country. But the Tsars have always exercised a strongly idiosyncratic influence upon that. I was thinking particularly of Alexander's initial apparent prediliction towards Napoleon - and of Tsar Paul's pro-Prussian attitudes. Russian thinking had been whipsawed more than once from Peter the Great to Alexander I. If Alexander had not been Tsar, I personally hesitate to predict which way Russia would have gone - how would Paul have fared against Napoleon? Not as well as Alexander I suspect.
Robert A. Mosher