European Train Station

I'm not aware of any such resource but if it's available anywhere, probably on Deutschebahn or other national rail websites. In my experience, though most major European train stations show a fairly limited variety in layout. Most of the time, the connection platforms all lie parallel to each other. The one variable, though, is the location of the Metro (if the city has one).

Here is a 3D map of the Zurich train station:
http://tinyurl.com/4ewgnc
and here is a map of the new station in Berlin:
http://tinyurl.com/4ldo52

There may be a few others. Do a search for the specific station you want at wikipedia.org, and if there is a map available there will be a link to it.

Most airports have a web site that shows layouts for that airport. I would guess that the city and/or train station would have a similar site. I would try googling the the train station by name.

Yes, the connections are often tight, and I suppose it would help at the really big stations to have a sense of the lay-out. Some station are (Kopfbahnhof), meaning dead-end, meaning you should head towards the front of the train to be able to get around to other rails.
It helps if you look up on which platform your train arrives/departs.
Best suggestion is:
look at the signs for the platform numbers and follow the signs and your instincts to the correct platform.

I try to avoid stations without elevators, it can be stress to lug a heavy suitcase from one end to another in a few minutes, even for us Europeans ;-))

But as stressful as it sounds, those few minutes are usually enough to make your connection, the stations are laid out that way, and the signs are everywhere and pretty intuitively designed.
Should your train be delayed, the connecting trains will wait a reasonable amount of time.