The point of it is to show that you've got a plan and know how much it's going to cost you etc. They want to know WHY you're going. They already know how (train/plane) but want the details.
SO if you can show that you're headed to France for 3 weeks to check out war memorials, before crossing to Amsterdam for some fun and out through Munich for Octoberfest, and have hostel bookings and the like, it shows that you've thought about it and have some idea of what you're doing, where you're going and maybe how you're going to survive (accommodation etc).
For example, some sites will suggest that you put together a travel plan. This could consist of the itinerary of your tour (if you're doing one), or otherwise - your accommodation, health insurance. Again, this site demands if you're booking through them that you include accommodation for every single night of your stay in the region, but I've had friends who have been issued visas without doing that.
- proof of accommodation for the duration of your stay
- proof of travel + health insurance
- proof of funds for the duration of your stay
Round trip reservation or itinerary with dates and flight numbers specifying entry and exit from Schengen state. Some Schengen authorities accept the itinerary when applying for the visa but request the original air- ticket when visa is collected (please verify).
Proof of sufficient funds for duration of stay, (Bank statement of the past three months) (min. amount required is different in each country – please verify with the relevant consular authority) Cash will not be accepted as proof of foreign exchange.
Travel/health/accident insurance: a one-page document stating that the applicant is covered by a Schengen Travel Medical Insurance, i.e. minimum medical coverage of the Rand equivalent of Euro 30.000 for all medical expenses, including repatriation dead or alive, occurring in any Schengen country.