75 miles is plenty long enough. The "trick" with longer distances is usually to break the ride down into shorter horizons. Riding 5km passes quicker than 50km, and gives you a morale boost when you tick it off.
Anyway, my comment around distraction is that it allows you to amuse yourself as you ride. Focussing on keeping cadence above a certain level (or speed, or some other measure) helps keep things, erm, focussed. I also find it occupies the mind (likewise with GPS units in general, when one starts playing games of arithmetic with the stats it is spitting out, although I am a mathematician by background). I also used to find cadence useful on hills, as I have a tendency to grind rather than spin - it's useful to have something to remind you that you are churning the pedals at <75rpm etc.
Complete aside. I've just noticed that one of the bikes I am looking at as an N+1 (a Giant TCR) has ANT built in. Yay for teh science.