"What level of atmospheric CO2 do you consider to be the ideal, and how would you go about reaching and maintaining your perceived ideal? What do you consider to be the ideal "global temperature" for Earth, and how would you measure it? "

It seems to me that controlling CO2 regionally is more important than global levels.
In cities you probably don't need more than 500 ppm- and most cities easily exceed this at the present.

But in regions in which crops are grown, you could want it to be at 1000 ppm or higher.

So if we could have the levels of CO2 currently in cities be in forest or crop areas, and the the level CO2 currently in forest or farming areas in cities then that would be closer to ideal.

As far as how you do this. Well, one should realize the CO2 is actually a resource rather than a pollutant. And one should find ways to make buying CO2 cheap- cheaper than water for instance.

As far as ideal temperature- most humans seem to prefer living in warmer climate- if given a choice they will select about 75 F. But human wear clothes and build houses to adapt to different temperatures. For crops you generally want temperatures to remain above freezing.
But humans prefer a variety of climates, generally they will vacation in warmer regions, but sometimes they also will go to colder regions.

But if global temperatures were 1-2 C cooler than they are at the moment, the result would be the glaciers would grow and growing glaciers will regionally cause cooler conditions which results in further glacier growth- which given enough time results in cooler global temperatures and glacier stacking up on continents- so global temperature 1 C cooler is not desirable. At current temperature most glaciers are retreating rather than advancing. Glaciers have be generally retreating for the last 10,000 [in the recent Little Ice Age this was not the case, but it has mostly been the case for thousands of years]. If global temperatures remain at around their current level, then eventually all the glaciers which grew during the Little Ice Age will melt- this will have little affect upon sea level- but regions where there was once glaciers will become on average, warmer.

If all the glacier which formed during the Little Ice Age, were to melt this would increase the global average temperature by some measurable amount. For instance some portion of the .6 C increase in global temperature of the 20th Century is probably related to the global glacier retreat which began about 150 years ago.
Another portion of the .6 C increase of 20th century, is probably due to increase in average ocean surface temperature, which was cooled during the Little Ice age. Though the majority of ocean temperature [the deep ocean] was probably not cooled due to the cooling period known as the Little Ice age- most of the ocean has been slowly warming for about 10,000 year, and will continue to warm unless temperatures return to average temperature of last major Ice Age.

So, if we continue around the current temperature, glacier continue to melt and the ocean continues to get warmer- and average global temperatures as result don't actually remain the same, but gradually rise. Now, the ocean temperature is about 3 C, it is not going to warm to say 4 C within a thousand years- unless you get a major event like a asteroid strike or a super volcano occurring in the ocean [a super volcano that dwarfs the current volcanic activity of the Mid-Atlantic ridge [cf: http://en.wikipedia.org/wiki/Mid-Atlantic_Ridge].

And whatever event was that causeed this, it is the event which would be the problem, not the 1 C rise of ocean temperature.

So as far as ideal temperature, the current temperature is pretty good. An increase in global temperature by say 3 C within a century would not be as good, but it would still not be as bad as a drop of temperature by say 2 C within a century [or ever]. An increase in global temperature by 3 C in a period of 500 years would be probably a good thing- though at point we might want to consider decreasing global temperature by as much as 1 C. Though at that time we might have a better idea of whether or not this would be desirable and how to effectively control global temperature.

Now, suppose that instead of global temperature rising around .6 C during the 20 Century, it had instead risen by about 3.6 C during the 20th Century. What would have been the consequences?

I think such a steep rise in temperature would scare people- therefore AL Gore would not been "necessary".

Tree lines would advance significantly. One could easily grow grapes in England. Oranges would perhaps now grow in Oregon. Glacier may retreat more and a higher percentage of them- perhaps all glaciers would retreat. And possible all glacier which formed during the Little Ice age would melted or be close to being melted.
Farmers would certainly notice the difference, and would have significantly longer growing seasons.

But it's doubtful that people living in urban areas would detect much change. First, Urban heat island affect probably has caused such increase temperature in growing urban areas. Second you can have regional variability which can easily exceeds this. And where you live in a city could result in having greater temperature difference. And since the development of such things as air conditioners, and insulation this has had a much larger affect upon how they experience weather- particularly when consider that nighttime temperatures could be most affected.

And sea level might have risen few inches higher. And generally one would have slightly more vegetation growth and more animals. No animal would gone extinct as a result, and polar bear would probably have as much growth in it's population as it did in the 20th Century.
Malaria would not have spread, and the whole host things claimed to be affected by global warming would not have resulted.

But such a rapid increase in global temperature would certainly be worthy of some serious concern. And one would scientist who are competent involved in the issue. And politicians might have had some pressure to spend money on the issue in serious manner instead of squandering it like they did.

So, in some ways a rise of 3 C might have been better than a .6 rise.