It is my understanding that it would take an infinite amount of energy to accelerate a craft up to the speed of light. Presuming an infinite universe you would effectively reduce the temperature of the universe to absolute Popsicle zero if you extracted that much entropy from within the universe. This is not a good way to make friends.
Additionally, you cannot land the craft at the speed of light; most runways are simply not that long. Decelerating from the speed of light would take forever, just like accelerating, and you would have expend and reinstall another infinite entropy back into the universe thus melting the Popsicle. This a good way to further irritate people.
The sum of two forevers is that you probably will not remember why, any why. It is also probable that business and politics will change while you are away for two-x forever. And even if you could manage to pull off a pissy little one-hundred light year circle to the corner store and back, that is still one-hundred years! Think ye that change will graciously await your return?
To continue, a speck of space dust at the speed of light amounts to a bit more than a chipped windshield. Something of a universe wide conflagration could be reasonably expected. Should any survive they will probably not speak to you for a while, like maybe the end of time.
If... you could somehow derive an infinite amount of energy from some non-universe source, and put it back, you would still be stuck with speed up-speed down and the great why? of it all. There is also the question of who is going to let you zoom around with two-x the sum total of the energy of the universe in a universe full of space dust.
There is also the other also of who might be residing in this non-universe place from whence you would pilfer your propulsion calories. Might they also be upset with your Popsicle-defrost antics? Might there be a lot of things that should be considered prior to presumption? How many friends are you trying to un-make?
O.K. So worm hole. How would you feel if someone bent, folded, mutilated and then spindled your living space with a worm hole? Need more be said? Go ahead and play pin the tail on the donkey across the universe if you wish. Just don't be upset if someone from the bent, folded, mutilated and spindled space folds your little part of the world into a cosmic omelet.
Apart from exotic configurations of scientific imagination this leaves one with the ages old practice of using the network of plasma streams that connect anything and everything of significance in the universe. Admittedly timeless travel is not glamorous against the glorious light of scientific technology and adventure. In fact it's a rather boring stone age tech, but it has been around for a very long time. The Sumerian Tablets of Destiny (coordinates and logistics of interstellar destination) have devolved into astrology and superstition, but they once served a timeless and practical purpose; shipping and receiving have the same time stamp.
You can do an interesting little trick with the Star of David(?). If you pull it apart top to bottom until the points touch you have an hour glass, which is infinite time. Push it back together and you get timeless. Cool, huh? If you pull it apart from the upper side you get infinite distance from zero distance; from the lower side you get infinite mass from mass-less. If you leave all six triangles out you get a cute flower thing with which to further confuse people.
Seeing how much fun that was you could also stand up the big plasma lensing ring magnet on top of the great pyre-amid and make it look like an eye and have even more fun distracting people.
This timeless travel stuff takes in the Tower of Babel, bottomless pits, the present three-hundred sixty-five day year and other stuff and, oddly enough, it relates directly to Double, Double, Toil and Trouble which, incidentally, was a very expensive and sophisticated operation, even more sophisticated than timeless travel.