Another way, and a bit cheaper is to use the Terraforming tree tool. It is only $3 per tree and you can alter demand and desirability for the land pretty quickly, or even bring back (some) abandoned buildings with a liberal planting of trees. The only problem is that if the plot is rebuilt into the more intensive use (i.e. you have moderate residential, but only getting single-family housing), you lose the trees that have been planted, and have to start again if you want to add more trees. Lastly, this really only works when you have demand for that type of housing (or commercial) on your RCI Demand meter.
