Yes, this was a super sweet game that made my afternoon a lot nicer. I also would have liked a map / quest list (I'm PRETTY sure I've been everywhere but I only just found the light house 20 minutes after beating the game...), but the exploratory aspect was really fun and it was short enough for me to get away with just wandering. God, this really let us live out the beautiful fantasy of paying off someone's college tuition, huh
Wow, I can't imagine missing the lighthouse, but it's definitely possible to reach the peak without doing all the other stuff. Having no way to point the camera is also a factor in missing things.
Did you find the tiny island with the gal selling sun hats? (I'm guessing you found the not-quite-tiny island with the smaller peak.)