It would be hard to get Russia out of Crimea as I think the majority of Crimean s' welcome them. Also it's former Soviet Union territory. Economic sanctions might be good, but to what end? Also it would be hard to get the many countries of Europe, dependent on Russian gas, on board. I mostly favor economic sanctions, but have some reservation as to what outcome we can realistically expect the Russians to do. Seems like they are not likely to let go of Crimea for quite a while at least.
A more likely scenario would be to push for better human rights within Russia which would also mean better treatment of minority groups in Crimea such as the Tartars and Ukrainians. Remember Russia's treatment of gay people as kind of a "canary in the coal mine" foretelling treatment of minority people's within regions under Russian rule.
The west can try to bolster Ukraine's economy and use it as an example of good governance as well as economics. Yesterday, I heard a good interview on Diane Rehm Show about this situation. Former US ambassador to Russia, Jack Matlock actually hinted, in this roundtable discussion, that Ukraine might be better off without trying to hang onto Crimea with it's Russian majority. We could push for better economy in Ukraine. I hear things are going quite well in Poland. Ukraine can be another example, like Poland of how to do things right.
Pushing for human rights is a good idea. The international community has a stake in what goes on within a sovereign country. For instance, neighbors have gotten stuck with floods of refugees from the appalling situation in Syria. I hear that refugees are 1/3 of Jordan's population these days. Jordan, some other countries and the international aid agencies are being overwhelmed.
Pushing for human rights, within sovereign nations, is important, but it seems very hard to convince the Russians to withdraw from Crimea. Maybe in the long run, some sort of international peace keeping deal can be worked out and continued pressure within organizations, such as the Organization for Security and Cooperation in Europe, of which the Russians, Europeans, US and many other countries are members.