Well, if there's one thing this thread and the others I've read has convinced me of, it's that a great many Russians (real Russians, not Russians as claimed by Russia) seem absolutely desperate for their country to be a super power again, and are willing to make themselves look like a laughingstock on the world stage if they can convince themselves of that for just a little while longer.
That's a bit drastic, I think, but the gist of it is correct. To phrase it a bit more friendly: After 1990 the West made the same mistakes that the Allies made in 1919, leaving a proud and powerful country with a terrrible economy, a chronic inferiority complex and no chance to integrate themselves with the global community in a way that fits their self-image. And even though the ideologies are radically different, we can see some patterns repeating themselves: A strong leader, nationalist rhethorics, land grabs in border regions, and an appeasement policy from the other states...
The conclusion I'd draw fom this is that the West needs a two-pronged strategy for Russia: On the one hand, a military buildup and a strong defense cooperation of the other European states (minus Belarus, maybe) is needed to prevent further actions like the one against Crimea, to reduce the chance of further appeasement and to show that Russia has no right to a 'sphere of influence' in the sense of controlling its neighboring countries. On the other hand, Russia needs to be integrated into the European community through a system of official cooperation in most if not all fields to take away the perceived need for a 'buffer zone' and replace the idea of a 'sphere of influence' with that of good neighborship, hopefully strengthening the Russian civil society and helping its economy to become less reliant on the export of resources.
TL;DR: Russia post-1990 is like Germany after 1919. That means the West should stand strong against Russian expansionism and agression, but also acknowledge that Russia feels threatened; therefore we (the European states that are not Russia or Belarus) must strengthen our military cooperation and defence capacity while at the same time helping Russia with its economy and integrating it further with the community of European states to take away the cause of Russia's worries and phantom pain.