solid state gear- leave on?

Turn it off. They do make some heat, and heat is ultimately the enemy of longevity. Tubes take a long time to settle in, so keeping them on makes some sense; for SS, just turn it on a few minutes before you start listening.

Also, daytime is generally peak electricity demand, so you are contributing in your own small way to both global warming and our dependence on Middle Eastern oil. Some things are more important than audio.

Maybe a more honest answer is that neither the heat from leaving it on all the time nor the effects of cycling it on and off are likely to have a significant effect on the longevity of SS gear. As to its impact on sound quality, speculate away.

To Tireguy: You confuse cycles and trends (and ignore the bulk of inconvenient evidence). But your attitude doesn't surprise me.