That sounds to be a hectic schedule for a little child of 4 years old....
As to Fujiyoshida trip:
You plan to see Yoshida Fire Festival, so Day 2 is 26 August 2009, right?
It may be hard for your kid to go there and come back to Shinjuku in one day.
That's an overnight festival, isn't that? Why don't you stay there?
As to Ghibli Museum, Mitaka:
Leaving Fujiyoshida Sta. in the morning on 27 August by 09:35, you will be able to enter Ghibli Museum by 12:30 if you have appointed the time and purchased the tickets in advance.
- Ghibli Museum, Mitaka: TICKETS
http://www.ghibli-museum.jp/en/ticket_information/As to Yokohama trip:
Yokohama Hakkeijima Sea Paradise seems to have plenty of attractions related to marine creatures, presumably too many for a little child to enjoy in a few hours, even if you can persuade your kid to limit them to those in the aquarium side.
Spots suggested by Uco-san sound to me better if you make a one-day round trip to Yokohama with a little child.
As to Mother Farm:
I suppose Mother Farm, which is not in Kimitsu but in Futtsu City, is ready to welcome little children.
If the day falls on 29 or 30 August 2009, then a direct bus is available from the east entrance of Kisarazu Sta. Another option is to catch a local bus from Sanukimachi Sta.
Only a few trains stop at the nearest Sanukimachi Sta. Probably it's better to stay in the place near a station (between Chiba and Narita Airport) at which Rapid Airport Narita trains stop.
As to hotel reservation:
Considering probability of bad weathers to suspend train operations, such as a storm by a typhoon, it may be a good choice to book guest rooms of the same hotel for consecutive days. You will arrive 2 days before Day 1, so I think you can reserve two hotels for Days 2 and 5 then cancel one easily judging from weather forecasts. I guess no charge is required for canceling 3 days before.
As to gaps in prices and Saitama trip:
Mitaka in Tokyo, Koshigaya in Saitama and Yokohama in Kanagawa are located to the different directions of Shinjuku.
Sorry, I see no reason for you to drop by Koshigaya, taking your kid along for such a long time and distance in only two days.
And, I can not guess why you plan to stay in Shinjuku where presumably accommodation prices are at higher rate, while on the other hand you care gaps in prices of goods between Tokyo's urban spots and its suburb in Saitama.
Even the urban area of Tokyo is not filled with retail shops of popular high-class brands. I suppose "big supermarkets like Jusco" exist here and there in and around Tokyo.
If you with your kid visit Ueno, Mitaka, Yokohama this time, I think it's better to leave nice spots in Saitama until the next time.
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