Hi Billy Ocean,
I took my DS to London when he was 18 months old. We decided to split the trip, and stopped in KL on the way, and Tokyo on the way back. That was one of the best things that we could have done, as it broke up the trip. As far as car seat goes, we planned (and did) hire a car while in the UK, so I took an old carseat with me from home, and then donated it in Scotland before coming home. We knew that we didn't need it for Japan as we caught the subway to our accom. Also we bought a portable DVD player. It was great on the long haul flights. If you are not buying your child a seat, then when you get on the plane, have a chat with the air hostess and ask them if they can move you so that you can have a spare seat. We managed to have a spare seat on all 4 of the long haul flights, and that made a great difference. This was even on full flights!
All in all, we did 9 flights, and I must say, J was an angel. The only flight he was upset on was the Syd/Melb flight of the way home.
I never even thought about pawer points in the hotels. It was a non issue though, as most of them are fairly well covered. You could always shove a chair in front if you needed. It is good to try and get a place that either has a seperate bedroom, or a partitioned area, as it might mean that you have to hang in the dark at baby bed time. In Japan and KL we didn't have a sep area. Dh and I ended up going out seperately for dinner while the other sat in the room listening to the ipod until J fell asleep. Anyway i was tired from the flight, so didn't mind the early night anyway.

The best advice that I have to give is relax about it. So many people said that I was mad to take an 18 month old on such a big trip, but he LOVED it. He liked the planes, he loved sight seeing, and was generally a pleasure.
Good luck.