I just finished the Seattle to Portland (STP) ride - 205 miles, in two days (I like to look around). Last year I used Hammer gel and Sustained Energy with pretty good sucess. This year I used their new product called Perpetuem, along with Hammer gel (for that extra boost). Perpetuem seems to sustain me better between major stops (10-15 miles) than S.E. The only caveat is to test it out on a shorter ride, say 40-60 miles to fine tune, and you need to drink additional water, besides the water used in making the Perpetuem. I mix 3 scoops per 28 oz. of water (they include a sheet on mixing), that's because I weight about 195 but can keep up a good 18-20 mph avg. for about 10 miles before stopping to relieve myself.
Good luck