I like to do long distance touring (not on the SM) and am not opposed to putting on the miles. As for getting tired, that depends on the sort of riding. Scenic mountain passes with lots of twisties vs. riding across the plains or through a big city.

For me per day.

I would have to say 300-400 on interesting roads. 500-800 on boring roads. Taking regular breaks helps.

05 speedmaster - 1100cc, 11:1 racing pistons, Carillo rods, thunderbike cams, ported and polished head, 2mm over intake and exhaust valves, Barnett kevlar clutch, scepter pipes, oversize manifolds, 45mm HSR's, TTP stage 4 firestarter