I'm planning on doing my first century this summer and the most I've ridden on a single ride was about 70 miles and I've done that exact same ride three times. I did well on that particular ride and I had energy to spare, but there were some terrible climbs that made me wnt to go home! That feeling only lasted during the climb I felt goofy for having those thoughts once I was over the hill, but funny thing is: they always pop up on the devilish climbs.
I love the tips on this thread and I have to say that I'm one of those guys that SWEATS LIKE CRAAAAAAAAZY! Not a little perspiration, I'm soaked after about 25 miles, so my hydration is a lot different than most folks. I have the larger Camelbak bottles and I go through two of those and a smaller, frozen bottle in my middle jersey pocket in one 20 mile ride, so I'll need to either stop often to get more fluid refills or carry more on me. I don't like the camelbak backpacks because of the weight and the lack of air circulation. I usually stop at convenience stores at least three times on my 70 mile rides.
I used to be a paramedic of 12 years, so I'm good at preventing myself from becoming a heat casualty. Thank you all for the wonderful comments on the subject and I'm looking forward to seeing ore comments that will help me stay prepared for my first century ride. I'll come back and post my results of what I did correctly and what I should of done correctly to help better prepare future century riders. Happy riding everybody!