First I want to know...
Can I be assured I will come back from any point in history? How reliable is this time machine? Am I protected, if I accidentally land in some era that's inhospitable to life? I mean, if we're talking the TARDIS, then no way. Nothing against the TARDIS itself, but that guy driving it is totally unreliable, and I'm not going to risk my family thinking I'm kidnapped or dead, just because he overshot the target and dropped me off a year late.
If it's a completely reliable machine... then I want to see what this world looks like ten thousand years from now. Are humans still around? Are they recognizably human? What do our social structures look like? What have we done to the planet? Have we successfully colonized other planets?
The one thing that frustrates me most about only getting to live 100 years (give or take a decade) is the fact that I will never get to see the rest of the story. At least, not as the person I am now.