I always thought that long cranks were better for taller riders because they allowed longer legs to spin in bigger circles. It turns out there's lots of research to show that this isn't the case:
http://www.powercranks.com/cld.html
http://sheldonbrown.com/cranks.html
TL;DR: If you are running a single speed or a fixed gear then longer cranks help provide more leverage but if you have gears then this ceases to matter.
I having trouble imagining my 36" legs being happy on 145mm cranks. Zinn seems to agree with me and offers some super long cranks:
http://zinncycles.com/Zinn/index.php/custom-cranks
http://bicyclecranklength.blogspot.ca/
And if you believe that then you should calculate your optimal crank length using this calculator:
http://www.nettally.com/palmk/crankset.html … though this doesn't factor for ground clearance.
I'm a similar height to you and KK and have experimented with different length cranks over the years on my road bikes, CX bikes, XC bikes and FR bikes. I always come back to 180mm cranks on my road, CX and XC bikes as THE cranks that feel the most natural for me. For my go-fast bikes it is definetly 180mm (haven't tried longer because they're very uncommon). For my Nomad3, I've thrown on some Next XL Cinch cranks in their longest length, 175mm. I've chosen to make a compromise because:
1/ I'm not looking to punish myself on the climbs when riding this bike.
2/ It has a low bb and 165mm travel.
3/ The Next SL cranks are so bloody nice and light.
I'm not convinced that there is no difference with crank lengths because I haven't read any really good scientific studies proving the theory either way. I can imagine that it would make less difference on a road bike where speeds are generally higher and cadence is up but I'm convinced that it does make a difference on a mountain bike. There are many instances where I'll be almost stalled out or climbing a steep hill in my lowest gear when a longer cranks is definitely advantageous. I'm rarely spinning a decent cadence on my mtb and don't worry too much about the odd pedal strike so the longer cranks are an advantage.
I liken this to the argument made that 29er tires have the same contact area as 26" tires. This is an oversimplification that ignores the shape of the contact patch as well as the change in mechanical friction caused by having different knobs in contact with the ground with the longer contact patch of a 29er tire. Mostly true on a road bike but not at all true on a mountain bike.