How do you juggle job offers?

I am graduating from college in Texas and have applied for a lot of jobs in my field. I mean a LOT of a jobs. Some of them are at great companies that probably get a lot of qualified applicants, and some of them are sub-par companies that I have applied to as a “back up”. I feel bad because I sort of regret applying to these “back-up” companies because I find myself not very excited about the work that they do at all (this is for a creative position and their creative portfolios are somewhat crappy). But a job is a job, right?

My question is: In the (unlikely scenario) that I get a job offer from one of these “back-up” companies, I’ll probably want to wait to hear back from my first-choice companies before I make any final decisions. What do I do in this situation? Do I accept the job offer, and on the off-chance that I hear back from someone better, drop the back-up and take the better company? How do I tell them in the most professional manner possible that I might need more time?

I know it’s unrealistic to expect to be stressed about choosing between job offers in an economy like this, but I would like to be prepared for all situations so that I don’t end up blowing any chances.