Best app to use iPhone/iPad as screen for your Mac/PC?

Either as an extended desktop or mirror, or better yet, to fully control said computer away from home via the tablet. What sparked interest is the inability to watch that old gamespot Wii launch marathon on IOS, while the family Mac is tied up with homework projects, I'm hoping I can run the video in the background of our Mac but front and center on the iPad. Basically, I'm asking what turns an iPad into a wii u, lol. Thanks in advance.

...can you do that at all? That sounds fucking glorious.

I know you can use the LogMeIn app on an iPad to control your computer, that's all I can think of.

Air Display

I use Splashtop. It works OK.