There are lots of other things we can do before doing something as drastic and potentially irreversible as geoengineering. Chapter 17 of the IPCC Fourth Assessment Report (AR4) Working Group II Report "Impacts, Adaptation and Vulnerability" is a good place to start.
http://www.ipcc.ch/pdf/assessment-report/ar4/wg2/ar4-wg2-chapter17.pdf
Another list is in a report from the National Institute of Environmental Science in Japan entitled "A Dozen Actions towards Low-Carbon Societies (LCSs)":
http://2050.nies.go.jp/material/2050_LCS_Scenarios_Actions_English_080715.pdf

"Non-regrettable" is a term that has been suggested as a potential criterion for selection of countermeasures for climate change. Basically, it means that we should put priority on adoption of measures, such as energy conservation, diversification of energy technologies away from fossil fuels and planting trees, that would be beneficial even if it turned out that climate change was not such a big problem.
http://www.carbon-partnership.com/publicationDocs/Aug%202006%20NEW%20NEW%20pp25-27.pdf

It seems pretty clear to me that "geoengineering" is a pretty "regrettable" technology - not only will it incur a large cost to carry out, but there could be numerous long-term consequences, some of which we may not even be aware of right now. One danger is that proposing "quick fixes" (albeit rather expensive!) such as geoengineering might make people more complacent about adopting other smaller, and possibly more tedious, measures such as driving less and walking/cycling more. So while it is somewhat comforting to know that there are some "last resort" measures that are available to us, we should definitely focus on those common-sense "close to home" solutions, "non-regrettable" solutions that we should do anyway for health and closeness to nature and furthermore that empower us personally to be part of the solution.