I only have time for one VERY quick comment right now. Before deciding on any railpass or train tickets, you need to seriously reconsider your plans. Trying to hit 8 cities in 4 countries in 15 days is almost impossible. Not impossible to do physically - but impossible to do if you want to see anything at all.

I agree with Janisj. Too many cities.

If I were you I'd get a "best of Europe" guidebook or Rick Steves "Europe Through the Back Door" and do some reading.

Thank you Janisj.
we think, we shall have to drop some places. we shall only include Germany, Holland and France. Germany (Frankfurt) in any case is our starting and ending city as we reach and leave from there. Same day of our arrival at Frankfurt, we can reach Amsterdam (Holland). on second day in amsetdam we take a Holland tour of 8 hours and the 3rd day we take a canal tour. This gives us a view of Holland and 3rd night we leave for Paris. next 7 days in France and the remaining 4 days in Germany. Our taste is to see places outside the cites rather than spending time in cities. we think that with your valuable suggestion, we shall be able to accommodate the whole programme in 15 days
i still would need some advice on train tickets
Thanks once again

A couple of notes:

You are trying to do way to much in too little time

You should consider open jaws flights - into the first city and home from the last - this will save you going in a circle and won;t cost any more

If you really want to see countryside primarily then you may find that car is better than train (IMHO the best choice between large cities)

If you post you itinerary - how many night where - people may be able to help you organize your thinking

But as it is you are not really seeing many of the key sights (a canal tour is a very small part of what there is to see/do in Amsterdam)

By Agde, what do you mean, Cap d'agde on the Med? It's quite a hike from there to Salzburg.

In July it will be absolutely heaving with holiday makers. It has a small old town but is primarily a new-build town and marina. Lovely Med views

Is it an abbreviation for another location? I hope.

I think before even wondering about tickets, find out if the proposed routing is even possible. Use www.bahn.com and plug in your destinations. The July 2013 schedule are not out yet, but you can use the same days of the week in January 2013 to get an idea. The train schedule does not change that much. If the routing is impossible using January dates, it is either still impossible in July or just slightly easier in July than in January.

When you mention starting in Frankfurt and ending in Frankfurt, is it just your current thinking or have you already constrained yourself by having purchased roundtrip tickets to Frankfurt?

thanks greg. nothing is fixed yet. just trying to figure out what is the best way. Thank u very much for raisng certain concern on the route. we have not still bought a rail ticket. I have already dropped salzberg from my trip - thanks to Janisj who pointed out that the travel plan is too heavy for us. So that suggestion was too helpful. but we still want to visit Amsterdam, Paris, Agde and then back to Frankfurt. If possible we shall go to Zugspitz in Germany while on the way back to Frankfurt. We shall be satisfied with this Itinerary.
Thanks once again

I assume you are coming from Asia and spending a lot of money on this trip. Instead of "being able to reach" someplace or "getting a view" of someplace, you should be focusing on actual enjoyment of the trip and the reality of the logistics, which even once you revised the itinerary, are going to catapult you into a series of days doing little but getting to and from train stations and finding your way around new places = lots of time lost that you could have used to enjoy your trip.
Get open-jaw tickets - into the first city and out of the last - so you're not wasting time backtracking. Don't buy a railpass until you absolutely know what your itinerary is and have compared the price of the pass with point-to-point tickets.

For a first trip to Europe, and with 15 days (which really isn't much and will FLY by, especially if you want to visit more than a country or two), and with your stated objective of wanting to see countryside as well as cities (how will you get to the countryside, by the way), I would pick three places in at most three countries; even then, you'll actually have only 12 days once you account for getting from one place to the next.

And what's the deal with Agde? Do you mean Cap d'Agde? If you have a familial or business connection there, it might make sense, but otherwise, no. And the logistics of getting there and then from there to somewhere else are going to throw a wrench into any plans.

What is Frankfurt for this trip? Just an airport or a destination?

I am not sure you have plugged in your destinations into www.bahn.com to see what you are up against. Look at a map of the area of interest, locate your proposed destinations, and compute travel times using the bahn web site. By insisting on putting Agde in the middle, you spend time getting there and then again getting out of it. Look at Agde-Frankfurt, Agde-Garmisch (which is a 13hr+ trip!!!) etc. You don't have that many days.