Hmm. I briefly, sort of covered this in an If Meerkats Could… post, but I can re-examine the notion once more.
The inherent risk with time travel, is that you might do something that makes the world considerably more dangerous, or that ruins the lives of the very people you want to help. History is filled with ‘what if’ moments. What if you saved Arch Duke Ferdinand from assassination? Would you prevent World War I, or would it erupt in a different, even worse way? What if you went back to Ancient Rome, and stopped the rise of emperors? How differently would civilisation play out if Rome remained a republic? The unravelling of history has unimaginable consequences, so the only real option would be (if you absolutely had to use the time machine at all) to observe.
To that end, it would be fascinating to see some of my personal ancestors. I did a fair bit of work into tracing my family tree, and I could use a time machine to see some of my past relatives. Some struck me as being quite formidable, and to see them would be a richly rewarding experience. Some experienced heart-breaking tragedies, yet carried on, in a world that treated them like outcasts.
In short, I would use a time machine to observe major historical events, and I would also use it to watch my ancestors, to get a glimpse of their lives, to understand what they went through.