If you has a time machine...

[yesyes]

another idea. I'd go back to the time when they decided to stop teaching spelling in British schools and prevent it from happening.

[pete_l]

I'd go forward to a certain day in 2156 so I could be the star guest at my own 200th birthday party (well, you can always hope )

[ScruffyOne]

I'd go back and see all the great gigs that happened before i was old enough/born. then I'd go back to ancient egypt and find out exactly when the pyramids were built

[Talitha]

I'd love to observe the Great Bombardment from a safe place, but the OP stated "your final destination is a place on Earth".

So, my choice would be to witness the creation of Stonehenge, Avebury and the other local associated sites.

Absolutely fascinating stuff!!

[Beulah]

A certain enlightened Comprehensive school in Somerset, early summer's afternoon, 1986....

I'd be sitting at the back in a huge dusty main hall, surrounded by hundreds of smelly pupils with backcombed hair, leggings, ties worn the skinny way round...

And at the front, Patrick Moore giving a speech about astronomy....

I was actually there on that day in 1986 - but despite enjoying the night sky as a young teen, I was too much into fashion, David Bowie, The Cure and people of the opposite gender to fully comprehend the enormity of having such an illustrious person in our school.

This time round I'd listen to what he spoke about, not stare out of the window, waiting for 3:15pm......

That's pretty much all I could think of. Most of the past I'd prefer not to visit, thanks.