Hi Kevin,
We are located in Placerville, CA. Here is a link to our average weather history:
http://www.weather.com/weather/wxclimatology/monthly/graph/95667
We get roughly 35 - 40 inches of rainfall per year (we have to irrigate a bit in the summer when rainfall is minimal). We grow Douglas Fir, Nordmann Fir, and Redwood. The neighbors grow the same species, with some White Fir and Blue Spruce.
So far, the work for us has been minimal; however, the prior homeowners did the hard part of establishing the trees for us. I would recommend avoiding trees that require intensive pruning, and I would suggest a tree choice that lets nature do the work for you. I would also suggest that you plant several different species, because people seem to be very set on buying certain species (this even included the redwoods). Most people bought our Douglas Firs. Regarding redwoods, they are a pain to take care of, because they have nasty thorns and stiff needles. It should be noted that I do not have any prior experience in generating income from land and that when I say "minimal," I am just thinking it was not very burdensome to my lifestyle. There could be better options to generate income for you and your land.
Prior to jumping into a Christmas Tree Farm, I would definitely consider the location of my land (you might need intensive marketing if you don't have good road frontage), and I would consider the number of customers I could expect to get given the population of my area. I think that customers also get a certain thrill from hunting for the perfect tree, so I would shoot for 2+ acres of planted trees at the very least.
Daniel