I Went to London on Friday and saw the renovated Waterloo Main Line Station with the new balcony area being open, a few more shops up there will be trading soon. I thought it looked very good and hopefully it will enhance the station and ease congestion on the main concourse.
You can have a drink and, or something to eat, whilst looking down on the people below.
(The only scruffy area IMO was on the main course above the old eurostar area, where there were still some half dozen approx food stalls.)
I did note that there seems to be a big left luggage in the eurostar area too which I have not noticed before, maybe just for the olympic period.
St. Pancras is very good of course, I have not yet seen the new Kings Cross, (The only thing with the LUL station at KX.STP is that there are very long walks from the main line platforms to the LUL Entrances, then very long walks to the various deep level tube lines.)
Marylebone is good too, but I do agree with an above remark about the long walk to the newer reopened platforms, I guess there must be something in the way nearer the concourse which is why they they were built that way.