Great thread! I just joined this forum, having learned of it from BikeJournal. Hope it's okay if I throw in my 2 cents...
It's a challenge to find food that works for a double, but most of the rides I have been on have been so well supported with a variety of things so you can experiment and find out what works for you. I particularly like when they have the hammer gel you can fill your flask with.
Some things that have worked for me are:
v8 - I had 9 v8s during the Death Ride last year and frankly was too tired to keep track at the Mt. Tam Double. For my other doubles, I probably had at least 5. LOVE v8!! I Know some folks who will fill one of their bottles with the stuff.
HammerGel - I have decided I like banana best. Not too sweet. But I prefer the real thing... next...
Dried bananas - my secret weapon. Not "banana chips" but actual chewy dried bananas. You can get them in bulk food section at Whole Foods. I also have a friend who dries them herself with a bit of honey in them. It's a little over the top, but the end product is amazing.
Noah's bagels - For Davis (my first double), we got salt bagels and I carried one with me on the ride. There is also a stick-like bagel thing they have that is wheaty and fruity and nutty. It took me about 2 hours to eat the thing, 1 bite at a time from my back pocket. That was great.
Wheat thins - yum! Very good if your stomach is getting at all iffy.
Nuts.
I pretty much only drink the Power Bar Endurance sports drink. And water. I will throw in a coke or mountain dew, but not til very late in the ride.
I have found that a bento box is only good for me on rides where there's not a lot of out of the saddle climbing. If I am out of the saddle a lot, the bento hits my legs so then I climb all wonky and my knee hurts. I may just have big legs. Well, I know I do!
I have a friend who is a raw food vegan who trained for and rode the death ride with me. I was amazed that he could literally fuel himself only on figs and dates for a ride like that. I say that to make the point that everyone's different, and what works for some may not work for all!
Sarah