Ally Pally is one of my favourite shows also. 60+ years ago my friends and I would catch a 233 to the Palace to fly our balsa wood planes. In later years, we would drive up to walk the dogs with my Mum and Dad. (After he was widowed, my Dad took a nun to watch a file in the Great Hall, but that's a different story!).
From the terraces, I can still see my childhood home and the site of my school, whilst the views of London are different on every occasion. My Dad used to maintain that it was going to rain if you could see the mast of the Crystal Palace transmitter!
In terms of the exhibition, I find the smaller room is interesting because of the specialist traders. There used to be one stand that always had kit-built LNER coaches and i was fortunate to acquire both an 8 coach suburban articulated set and also a Leeds triplet restaurant set. However, in general, I prefer the Great Hall for it's light and airiness.
Sadly, it is unlikely I shall be attending this year unless the Covid risk falls or the organiser toughens entrance requirements, as last month I spent a week in hospital with pneumonia.