I'd track a nice sized rocky asteroid coming close to earth, catch up to it, and build a condo on it with a few engines and away I'd go to near the speed of light, slamming through a few stars for fuel and away I'd go.

I don't want one... no place to go! Unless I want to fly low to impress the locals. Its like owning a atomic bomb. What you going to do with it? Now give me a jet fighter plane. It's amazing how 7 thing take off - takes your breath away.

I'd just have a Xeelee Nightfighter (from Stephen Baxter's novels, for those who don't know what I'm on about).

Have you ever ran into a tree? I am into art not science... Past civilizations been measured not only by technology advances but by their contribution to the plastic arts. The first thing you ever knew about Egypt was the pyramids not their chariots. You go ahead and play noah on 21st century.

Does it have to use existing technology? Also, how does creating a vacuum achieve propulsion in space?

It is hard to make a useful centrifuge for the astronauts. You need it to spin at less than 2 rotations per minute - otherwise the astronauts would get dizzy. [quora.com]

If you calculate the size it then needs to be to give the astronauts a reasonable gravity it becomes kinda wide. My quick and unchecked calculation gives 440 meter radius just to get 0.5g! So your spaceship would have to look more like a face forward flying hockey puck.

Mine would just be an interstellar hull protecting the AI core becuase WTF would try interstellar travel with mortal organic bodies. Solar sails should work fine since AI doesnt care about travel speed

Yeah, I'm really appreciating some real science in my science fiction. I've always hated spaceships designed based on a horizontal access, like the Enterprise in Star Trek. They should be based on a vertical access, because forward thrust would create downward force to mimic gravity. This combined with a centrifugal wheel or sphere for crew quarters, and you're off and running to romp around the solar system.

Death Star. Definitely. Death Star.

OK, I have to ask, why 303 feet long?
I would opt for something like in Dune, a ship that goes inside a space warp and you come out the other side

does it have protection in the front for the possibility of space rocks etc like in the movie Passengers