It seems I was pretty close to the end of Ganon’s Tower when I died previously. I hadn’t explored all of it, but seems I didn’t need to in the end. A little further than I reached last time, there was another giant snake thing like at the end of another dungeon (as well as the three not-so-giant snakes from the Desert Palace), so it had started to become a bit SuckySuck(TM). Even more so when I reached the end boss of the dungeon – Agahnim again. OK, so he split into three this time, but was actually much easier to kill. And then – [spoiler]!
End of game boss time. Before that, I nipped over to the witches to get some potions, and then it was into the hole in the top of the pyramid. Ganon was waiting!
I died once on him, mainly because I wasn’t actually watching my health and didn’t realise it was about to run out. He was pretty simple to kill, though, taking only a few hits and being easy to avoid when he attacked. The only hard bit was not being knocked “out of the arena”, and out of the pyramid – meaning I had to start again once too.
And then he was dead. The Tri-Force was mine to command, the Maidens were all saved, and peace and happiness yadda yadda yadda. WIN!