Kyoto - (JR Kyoto Line) - Osaka - (walk) - Floating Garden Observatory - (walk) - Osaka - (JR Loop Line) - Osakajokoen - (walk) - Osaka Castle and Aqualine - (walk) - Osakajokoen - (JR Loop and Kyoto Line via Osaka) - Kyoto

or the other way around

cost of transportation

1480 yen per person

It is quite a long walk from Osaka Station to the Floating Garden Observatory (about 10-15 minutes), so if that is too much for your parents, you might want to consider a taxi (about 700 yen one way).

Also, would you happen to know the most direct route to get from Shinagawa to Tsukiji fish market and the cost? We will be in Tokyo prior to going to Kyoto and my father wants to visit the fish market.

The Daimon route includes Toei subway Asakusa Line. You can not find a Keikyu platform at Daimon on your way back.
Shinagawa of Keikyu (Track 2)
| Keikyu Line, around 5 minutes;
(Sengakuji: no transfer if on a direct train)
| Toei subway Asakusa Line;
Daimon (Change to Track 3)
| Toei subway Oedo Line, within 5 minutes;
Tsukijishijo
| Walk
Tsukiji Market.
- Time: about 30 minutes.
- Fares: 340 yen = 130 yen (Shinagawa - Sengakuji) + 210 yen (Sengakuji - Tsukijishijo).

- Tsukiji Market
http://www.tsukiji-market.or.jp/tukiji_e.htm
- Tsukiji Market: 2009 Calendar
http://www.tsukiji-market.or.jp/etc/calendar/2009.html
Red: Closed day; Blue: Extra open day.
- japan-guide.com: Tsukiji Market
http://www.japan-guide.com/e/e3021.html
Please refrain from using cameras whose auto-flash can not be deactivated.

Maybe it's better to first visit Osaka Castle from its west, taking a Osaka City Municipal bus (from Osaka Station Bus Terminal to Bambacho Bus Stop) for about 20 minutes.
When will you take this Osaka trip? Buses do not always run frequently for this section.

Qs and As (in Japanese) about Osaka Castle on this page say that the way from the direction of Tanimachi 4-chome via Otemon Gate is relatively flat, and you can come on this way even on a wheelchair. Bambacho Bus Stop is in the middle of this way.
http://www.osakacastle.net/osaka-castle/qa.html

In Osaka Station, no elevator exists between a platform and a transfer floor (M2F).
Also Municipal subway (Higashi-Umeda - Tanimachi 4-chome) is available, but I suppose taking a bus would be better than going up and down in two stations.

540 yen: Kyoto (Track 4 or 5) - Osaka (elevator on Kyoto side to 1F, South Exit).
200 yen: Osaka Station Bus Terminal (Line 102) - Bambacho Bus Stop.
200 yen: Bambacho Bus Stop (Line 102) - Osaka Station Bus Terminal.
660 yen: Taxi to Umeda Sky Building: Needless when you can get there on foot.
660 yen: Taxi to Osaka Station's South Exit.
540 yen: Osaka (Track 7, 8, 9, or 10) - Kyoto.

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