Tillig HO Elite is gorgeous, no doubt. But unless you are willing to spend the next 10 years building your layout I think they may be overkill. My philosophy is to have all aspects of my layout on the same 80% level. Call me an 80% guy. The remaining 20% are for folks that are retired and there is nothing wrong with that.
As far as your layout goes, you are fortunate to have a large dedicated room for it. I am no expert in layout but I would suggest to sign up with Model Railroader Magazine
http://www.trains.com/mrr/. It will give you access to a library of hundreds of track plans. I found that the Americans have a unique way of solving their space problems.
You may also want to add the benchwork into your plan, to see wether you will run into access problems. I had to tear down my previous layout because it just wasn't workable. Make a 3D drawing (google "Sketchup") of the room including bench work. Look here
http://www.anyrail.com/forum_en/tips_and_tricks/room_dimensions_and_work_bench-t16.0.html for more.
I am not familiar with Peco, but I hear they are first class. Walthers Code 83 (Shinohara) is very good quality too and they even make a double crossover ("Hosenträger"). It may be hard to get in Europe though.
One more note on noise. You cannot underestimate the amount of noise that all pre-ballasted track makes. Model track on cork roadbed is so much quieter. All my locos are DCC and have sound. When I run them on Fleischmann Profi I can barely hear the sound effects. I now wish I had used Roco LINE exclusively. Oh well.
