If you haven't done it before I strongly recommend the triple. Not only will you have lower gears, it'll give you a better selection of gears. And make sure that you have at least one gear lower than you think you'll need in case you have a bad day. On my first Death Ride I had a triple with a 30t granny and I made a custom 12-28 cassette. The 30x28 was overkill- for the first four passes I was in the 30x21 or 23. But on the last one I was suffering from hyponatremia (not knowing what it was at the time) and the heart rate I could maintain I could barely turn over the 30x28.