"that before you spend the huge amounts of money on the nuclear power plants, you suck up as much of the load as possible with the alternative methods."

You could say that we have been doing this for last 3 decades, if instead we had been building nuclear power plants during this time [which could have cost no money to federal or state governments {because nuclear, unlike alternative methods are competitive with coal and other conventional means of generating power} the result would been less of the other types of conventional power plants being built and operated.
During this 30 year period, it could have been easily possible to double our current use of nuclear power.

"Take China, which is widely blamed for the rapid rise in greenhouse-gas emissions. Indeed, China accounted for two-thirds of the more than 560 coal-fired power units built in 26 nations between 2002 and 2006. The Chinese plants boosted annual world CO2 emissions by 740 million tons (see chart). But in the next five years, China is slated \to slow its buildup by half, according to industry estimates, adding 333 million tons of new CO2 emissions every year. That's still the largest increase of any nation. But other nations appear intent on catching up.

...

For example, the United States is accelerating its buildup dramatically. In the past five years it built 2.7 gigawatts of new coal-fired generating capacity. But in the next five years, it is slated to add 37.7 gigawatts of capacity, enough to produce 247.8 million tons of CO2 per year, according to Platts. That would vault the US to second place –just ahead of India – in adding new capacity."

http://www.csmonitor.com/2007/0322/p01s04-wogi.html

So, roughly let's say Nuclear power took 1/2 of the growth in terms of coal plant increases.

Here another data point:

"Installed nuclear capacity initially rose relatively quickly, rising from less than 1 gigawatt (GW) in 1960 to 100 GW in the late 1970s, and 300 GW in the late 1980s. Since the late 1980s capacity has risen much more slowly, reaching 366 GW in 2005. Between around 1970 and 1990, more than 50 GW of capacity was under construction (peaking at over 150 GW in the late 70s and early 80s) — in 2005, around 25 GW of new capacity was planned. More than two-thirds of all nuclear plants ordered after January 1970 were eventually cancelled.
During the 1970s and 1980s rising economic costs (related to extended construction times largely due to regulatory changes and pressure-group litigation)."

http://en.wikipedia.org/wiki/Nuclear_power

So according to above we now have around 366 GW, so if we had doubled it, it would now be around 700 GW. Of the 350 GW increase, as I said above 1/2 of it- 175 GW took the place of coal power stations, this would mean we would produce about 1 billion tons less CO2 just from the Coal plants per year.
We also would saved a considerable amount in terms oil and natural gas use [and their emissions].
That means that over the decades, we would not have had tens of billions of CO2 emission- and in coming year save even more [say up to 100 billion tons of CO2. It means we would imported less oil and natural gas. And it means we probably would have met or exceeded the Kyoto target.