Well, I did it: both the Jidai Matsuri and the Kurama fire festival in one day with all three kids. A friend joined us at the Kurama festival with her three boys so it was the two of us and six kids. Quite the crowd and quite the adventure.
Here is what we did. Picked E up from school at 1pm- the usual time for Friday- went down to Nijo station and parked our bikes. With a one day pass on the subway we went to the Higashiyama Station. The jidai matsuri goes right past the station, so we just went up the steps and watched for a while. It wasn't as intimate as the Zuiki matsuri, but the costumes were good and it was impressive just in terms of the sheer numbers of people. I had thought that they would go through the eras in some sort of historical order, but no- they just seemed to be jumbled together: Tokugawa then Muromachi then Heian then sengoku. Still the kids liked the horses and the costumes. We only watch about 30-45 minutes of the procession and left during a lull. It probably would have continued longer, but we were fine with what we saw and wanted to head up toward Kurama. We hopped back on the subway and went all the way up north to the Kokusaikaikan station. We got there about 3:30 with only one major tantrum from 3 year old S who went without his nap. From the Kokusai kaikan staion it is about a 10 minute walk north to the Eiden Iwakura station (along the river just west of the subway exit #1). From there we were crammed inside the small Eiden train for the ride to Kurama. This was very uncomfortable, but I think that at least if you get on there you don't have to endure the crowded train for as long (maybe only 6 stops instead of 12). Once at Kurama we sat down in front of the station to eat our onigiri. There wasn't much in terms of things to eat there- none of the standard matsuri food- so I was glad we brought stuff- onigiri and snacks for keeping people happy. I am certainly not above using sweets to their full potential on outings like this one. We met up with B and her three boys there and proceeded to follow the directions of some of the many police officers who directed us behind a yellow tape. We were supposed to keep moving and I am glad we did, eventually we got beyond the major crowds further up the canyon and were really able to see the festival well. We were right close to a lot of the torches. First there were the young kids, and then the BIG torches. Unfortunately our camera couldn't really capture it- but there were lots of photographers with cameras that could- some directing their attention to the six gaijin kids staring intently at the bonfires. About halfway to the onsen, there were people drumming on the Taiko and some of the torch bearers swayed to the beat. It was pretty awesome. 3yr old S and others had a blast stomping out the cinders that had fallen to the street. We started back around 7:45, although that was perhaps too late. Yes the festival would keep going until midnight, but we thought we would be safe leaving then. We got caught in a major traffic jam heading back to the station area and then ushered through orderly Disneyland lines for the train once we got there. It took a while to get back on that crowded train again for the return journey, retracing our steps. I must say, the kids were really troopers. It was 10:30 or so before we got home, but it was fun and I would say very worth it. As we were walking up the steps all 3 of them said they had fun.
If you ever plan to do this, here is my recommendation: If you have the full day, watch the jidai matsuri starting from about 11 on the grounds of the imperial palace. It is the staging area and so most people will be there at once. Plus it is a little more picturesque to watch the procession on the grounds of palace than on the streets with a McDonalds or Lawson in the background. The procession starts at 12, and I bet it is an hour or two before the whole group passes through. Get some lunch and if you haven't already, get some food to take up to Kurama. I liked our route, but if you want a seat, you can wait in line at the Demachi Yanagi station. Probably if you are there close to 2 you might not have much trouble (you may have to let a train or two go by before getting to the front, but I wouldn't know for sure). Once you are in Kurama take a nice break-because this is a long day for anyone. There are a few restaurants there, but check for prices first- it could be expensive. Try to make your way uphill along the route as far as you can before 6pm. Once the fires start, gradually make your way down and head to the station not long after you've seen a few of the big torches carried by the young men of the town. It is possible to stay for more, but with kids this is about all you can hope for. I was saying to B that if I were young and single it might be fun to stay until the last train or even all night, but leaving at 7 or so would be best for the kids. Good luck to any who want to try this. I certainly thought it was worth it, but it made for a killer day.