I don't have enough experience with triples give you an exact answer on optimum chainring spacing. But when I was frustrated with the poor shifting on my Voyageur 650b, I chatted with the top mech ar my local LBS. He suggested the 48-36-24 combination and called it 'classic mountain bike gearing', which was useful since O was using Deore MTB derailleurs and cranks. Worked a charm, so did the same install (but with a Sugino crankset) on the Davidson and haven't felt any need to mess around with it. 48/12 combo gets me to the high 20's before spinning out, and the 24/34 combo lets me pull up any hill I've ever met.