That is a great deal on airfare.  I would only add one, maybe two cities in there.  The cities you listed are pretty close, you might be better off without a rail pass and just taking point to point trains.

2 weeks really is a short trip, and you are already planning on 3/4 places. You shouldn’t add more than 1 other city or your trip will consist primarily of traveling and not visiting. Based on the places you listed, Berlin seems to make the most sense. For rail, it would be smart to check the cost of point-to-point trips and compare them to a railpass. If you decide to go railpass, the Eurail 4-country select seems like a good bet. You can check PtP tix prices here:

http://reiseauskunft.bahn.de/bin/query.exe/en

hi,
i try to check on price of point-to-point ticket but it wouldn’t provide the cost unless i book the ticket. Is there another way?
My final itinerary is brussels (+bruges)-amsterdam-berlin-salzburg (+hallstatt)-fly to paris. those are the places i really want to go. now it’s just to figure how to get from point to point.
i don’t mind spending 2,3 days at a place
thank you for your advice

The die Bahn wesbite does work, but it looks like it’s not providing all (or most?) fares. You can also check the website below, but I don’t know that it will return all possible trains:

http://www.raileurope.com/us/rail/fares_schedules/index.htm