Thanks for the reply, I'm feeling more confident in staying the extra year now. I understand what you're saying about being tired of classes in the fifth year, but for me the fifth year would be a pretty light class load, so it shouldn't be too much of a grind. Something I hadn't considered too much either was having the chance to refine my interests, which I think will be a big benefit. I have worked on projects in composite materials, design, and computer vision, and liked them all. Having the time to narrow down what I would like to research will not only help my application but help me get more out of grad school. Good luck at your future school!
heh, I actually came in to my program trying to finish in three years, but due to course scheduling I had to stay for at least four years with a very light load. I started taking CS classes to fill out my schedule, and now I like it enough that I am considering staying even longer. Thanks for the advice, I will definitely talk to some professors before making any final decisions.