Travel up or down from earth in a future space ship?

Sice we're trying to make spaceships to travel the universe, why do we always want to got the same direction, towards pluto? There could be a planet or something if you go up or down from earth. I can't really word it correctly, sorry.

I think this is because we need less energy if we leave the solar system along a direction which lies in the plane of orbit of the planets- we can get gravitational slingshot effects by passing close to planets.

If we close to leave at a direction prependicular to the plane of the solar system, there is a large potential to climb out of using rocket power alone.

Also, it's more interesting to go via the other planets because we can take pictures of them. Since the solar system plane is orientated rather arbitrarily in the milky way, we might as well get some local snaps before we leave.

Do you think that the people behind those gigantic, multi-million dollar telescopes are just amateurs who don't know what they're doing? Do you really think there is a square millimeter of the sky that has not been thoroughly examined? If there were other planets in our solar system, we would know it, for certain, no matter what direction they were in. Outside of our solar system, there could be planets in any direction at all, of course, but we have no way of sending a probe to a destination outside our solar system.