Ahh Ok 767Bill, I didnt mean to offend your intelligence.. I understand now.
Well like said before the higher the better.
There are charts out there that actually give you max altitudes for a given distance. there is a distance index and a time index etc...
by looking at the distance you want to fly you can find your optimum altitude. There are also time, fuel and distance to climb charts.. you can refer to this too for optimal altitudes..but they are not the best.
One of my old professors, total cocky jerk told me that in 'his' G5 the most efficient way to go from A to B was not in a direct line but rathar in a circumnavigational fashion, the rationale behind it was being able to climb higher into thinner air for the cruise portion.