Multiple maps:
There is no reason that you cannot map for best output at all points, and then tune the cruise region lean for good fuel consumption. In fact, I do this regularly. The difference in output at cruise (up to 8% TPS) between power producing mixture ratios, and leaner ratios is so small that it is inconsequential to output. Yet the fuel mileage gains can be substantial. You just need to add more fuel for acceleration compensation - when you grab the throttle. This way you have good mileage, yet full power is there when you want it.
I do this for the road race bikes as well - less fuel needed, means the bike is easier to throw around in the turns. At 6.25 lbs per gallon, located high on the frame, this is a good place to reduce weight.
Now mapping less agressively for riding in the rain, can be a good idea, as can a second map for a different fuel - pump gas/race gas, 87 octane/93 octane, pump gas/E85, etc.