I have a few places in time that I'd love to witness, write down, record, or something to take back to the present, if possible to do so with the time travel solution.
Think about it; religious and non-religious alike debate how old the Earth is, our origins, whether evolution is real, Pangaea, pizza with anchovies being edible or not - and just imagine if, through whatever method is theoretically possible, and without affecting causality, the time continuum, current time stream, what have you, one could go back and observe, in a safe manner, the origin of the universe? The beginnings of the human race?
If, we're to just assume that the Adam and Eve story is true as it was described in Genesis, one could interfere and possibly burn The Tree of the Knowledge of Good and Evil down as well as The Tree of Life, and create a future where no one ever dies; a true utopia.
Who can truly say with what we know now? Unfortunately, a lot of old knowledge was probably lost when the Library of Alexandria was burned down at the Roman Empire's zenith. Even the truths within the Bible itself (and by "truths," I mean the accounts that we are to believe to be primary sources that reported things as the authors understood them, not the life advice per se), be it the Old King James that fundamentalists traditionally refer to, what we have left of the original manuscripts, and the Catholic copy which was used when translating the documents that comprise the entirety of the Bible itself, could have been manipulated for Constantine's benefit when he ascended to the top of the Roman Empire, or what it had become by his time in world history.
One could time travel to these confusing points in history, perhaps gain more insight into things not so clear right now in our present day.
The only other place I could want to time travel is the possible end of the world, or the beginning of the end, if The Rapture and the Great Tribulation itself is indeed a something that will be a reality, as it appears how things are headed at the rate that the stage is being set if interpretations of the events to transpire are any close to what John, Daniel, Isaiah, Ezekiel, Jesus, Paul, Enoch and others were possibly trying to communicate to the best of their understanding. And if possible, I'd take that knowledge, as well as any evidence I've observed to the current timeline, and see what I could do to prevent it, and thus save the world from what would be, and could be playing out very soon, a series of events that could be comparable to the Plagues of Egypt, except on a global scale.