While an internship can be the single best differentiator for you in achieving job search success, it does come with some attached baggage. Namely, why would you want to work anywhere other than with the company you interned with?
The opportunity often exists to work for the company you interned with after graduation. That is, if you were a productive intern. While accepting a position with your internship employer can make your job search infinitely easier, doing so also limits your scope of opportunities to just one company. Would you consider marrying the first and only person you ever dated? Probably not. Yet that is what many students are doing when they go to work for the company where they interned. If the company is everything you ever wanted, if it provides you with opportunities for growth and advancement, if it helps you realize all your hopes and dreams—go for it. But then why are you reading this book? Probably because you want to know if there may be something better out there.
For most students, the company you interned with is just one of many potential employers to consider in the job search. Yet other employers will usually wonder why you chose not to work for the company where you interned. You will need to have a ready answer to this question, or you may end up looking like the unwanted leftover from another company's internship program. If there is an offer to return full-time after graduation, make sure you mention this fact in your correspondence (written, verbal, and during the course of the interview) and why you decided to consider other employers.
The strongest hand to play is when you have an open offer from your intern employer to return as a full-time employee after graduation. It will provide you with an offer in the bank, which can only be beaten by better offers. The net result is that it will intensify the competition for you as a prospective employee. Use your time wisely while the offer is still open, but do not put off a decision beyond the requested response date. Do not accept one offer, then continue shopping for a better offer. Work within the time frame given.