Another vote for elevenses bars
For a 2-3 hour ride at a good pace i tend to have a good breakfast , good old porridge with dried fruit hits the spot , i have tried it after a Sunday lunch and it sits to heavy for me .
During the ride i will be drinking regularly on a drink made from powdered glucose normally made half strength , or i have developed a tasted for the zero cal electrolyte stuff atm, i will eat an energy bar or a gel on the road after 20 + miles and i am normally ok till the end of the ride.
The longest ride i have done was 76 miles and i was told to eat little and often to keep my energy levels up , using a couple of gels and a couple of energy bars .
The more i ride the less i feel the need to eat on the go , maybe i am getting fitter or my body is getting used to using the energy more effectively, i did a 40 miler the other week and although we had a cake stop ( had a coffee) i did not feel the need for any energy.
I found glucotabs can be good as an instant boost .
I did read jam sanwhiches and bannanas were good, check this blog out.
http://cyclinginfo.co.uk/blog/cycling/cycling-food/