I feel somewhat guilty if I close the account as soon as the requirements to keep the offer are met.
You shouldn't. They're not doing it for you as a favor. Rest assured that in the aggregate, they are still making money by extending this offer.
I currently have an offer, that if done to the minimum of the requirements works out to about 100% APY. This seems a bit to good to be true, so I am a more than a little skeptical.
That does sound too good to be true... I'd make sure to triple-check the fine print.
My main question is, what is the down side of using these offers. Other than the obvious part of having to watch another account, and the time invested in opening and closing the account. Does the opening and closing of an account have a negative effect on your credit score? Is there any reason I should not take advantage of the offer, other than feeling guilty about planing on cutting ties with the bank from the begining when there goal is to bring me in and keep the account for the long term.
Unless they pull a credit check or extend credit to you, it shouldn't affect your credit score.