As Tempast said it's very blanket. How ever as a Classical Libertarian, Meaning I promote a fiscal agenda, with a moderate social position, I will try to offer a answer but it will also only be a blanket answer. To be honest getting down to all the factors in Business vs Labor unions is like dissecting a frog blindfolded with a dull knife. Collage lectures on the subject last 3 to 4 weeks.
Large business is a important part of fiscal stability They supply more jobs then the mom and pop business that are just as important. However we know that when a business gets greedy it starts doing things to further it's own profit margin instead of focusing on their responsibilities. Such is the case with AIG that had more assets from profit and not enough escrow to pay responsibility.(See AIG link)
People on this extreme figure that there is so much change from left to right control in the federal government that they have to take advantage while they can. Now pro labor is the addressing of the needs of the employee. When business puts it's interests and gains so high that the employee gets financially abused, IE time is money. The problem comes when the labor heads get so powerful they start running like the greedy large business. Instead of looking out for the little guy they lookout for the union. An example of this is The United Auto Workers (UAW) control and refusal to work with Chevy and Chrysler to lower labor costs. In fact 65 percent of Chrysler and 17.5 percent of General Motors is in The United Auto Workers control. (See Slate Magazine link).
Extreme left with a socialist agenda won't acknowledge that some labor unions go to far, thinking that in a socialist state the greedy is weeded out. As a result the greedy labor unions ride on socialist coat tails.
This is why we need balance in the three branches of federal government. All the parties that you ask about have a self interest agenda. While it both instance it's really is not the rule it is the exception most business and labor unions know that to go to far is not good for anyone. However the few that don't, their actions are what cause the most damage and spur fiscal irresponsibility. I include the politicians in that assent siting them as enablers.
Balance their voices and the results benefit the people witch is supposed to be represented by our elected officials.
The Fall of AIG (AIG)
How the UAW's new ownership stake in GM and Chrysler will defang the union. - By Daniel Gross - Slate Magazine