Congratulations!! I too recently completed my first 100miler, though in somewhat more organised circumstances at the Pro Tour Ride in the South West. 107 very lumpy miles with 3200m of climbing. I think the organisation made it easier, being surrounded by hundreds of other riders sharing the pain and spurring me on, having regular well stocked feed stops and generally buzzing off the adrenaline of a mass participant event. So really well done to you for having the determination to keep going on your own, when it is so easy to turn back as soon as the going gets tough.
That said, what surprised me was how physically ready I was for it. I have not even come close to 100 miles this year. My rides have been limited to short evening runs, the occasional weekend 40-50 miles and a few hill training sessions. Perhaps the best training I had was a 5 day holiday in the Southern Alps about two weeks prior to the event, where we cycled over 6 passes. I certainly felt like this took me to a level I've never been to before, but I was always aware that it was achieved in a very short space of time and that that strength/fitness might not last that long. Yet, even with 95 miles under the belt I still had the strength to really push on at the end.
The ride was actually far more of a learning experience, not about fitness so much, but about the bike, eating, drinking and patience! I had a bit of a nightmare ride, puncturing 5 times and running out of inner tubes. Luckily as the event was so organised I was able to profit off the support vehicles provided. Without them I may have been walking to the end. But they all frustrated my rhythm and my state of mind and by the 5th time I was ready to throw my bike off a cliff.
So I think what I learnt from it, was to prepare myself for the length of time it could take, and to stay patient in the face of the other disruptions that can occur in that space of time. Also, to take a good variety of food, because mule bars really aint that nice after the 45th one. Maybe the next time it will go a bit more smoothly, making for a very pleasant surprise! And yes, I'm very keen to do it again, if just to prove to myself I can do it in a far quicker time.
Anyway, sorry to hijack your post, just thought I'd share.