clip pedals are great if you are pedalling 'properly' (i.e. you have worked out the foot pivot that makes you pull up with the normally unemployed leg which is doing the upstroke). I must say it took me a month or so of thinking about this action before it came naturally, and in the end, being more of a cycle tourist than a racing cyclist, I decided on simple, comfortable 'touring' shoes (like a trainer, but with a metal or carbon insert in the sole to provide rigidity) combined with a pedal cage, Cages are very easy to get out of, and free you from the 'falling over' paranoia. Also, you can walk around in touring shoes, but try it with your clips!
Now, I ride anywhere up to 20 miles or so in normal clothing and trainers, because I can't be arsed, but admit that I average about 8-10mph now, whereas we toured at 12 -15. Maybe its being fat and 60+!?
Take my advice with salty pinches tho. I never was in the league of the gentlemen above. My best ever was 54miles in 2 hours 42, but that was on a mountain bike, and up over the downs to Brighton. I was happy anyway!