In general, I find that when a CD matures, the bank will try to roll it over into a low rate CD. Many wont allow you to put the money into a promotional rate. So, when I called Ally Bank a few days ago, I expected that I would need to cash out and look for a new CD. Instead, Ally offered me a retention bonus of 0.5%. So the new 1 year Cd would have a rate of 2.34% (1.84% plus the retention bonus). This is the best rate available anywhere. In addition, they allowed me to put additional money into the CD at that rate.
I was also very pleased with their customer service- I was actually able to speak to a real person, with minimal hold time, on three occasions and they were helpful in terms of arranging a wire transfer of more money into the account.