When I started building my layout about 8 months ago, I looked at my "available" space and decided to go N scale so that I could get more railroad in that available space. My previous experiences with model railroading many years ago, was with HO scale. I was also shocked at how small things are in the beginning, but I have gotten used to it, mostly, and I am happy to be able to get more out of that available space. But, if you are unsure, then now is the time to make that decision.
Now, a story. The available space was in a room shared with my wife and her sewing machine and stuff. Recently a friend of hers was over and she had some HO stuff hanging around her home that was left behind by her husband when they divorced. I explained that I don't model in HO scale, and explained the available space as the main reason. I almost broke my neck when I did one of those old cartoon "double takes" as my wife says "Oh. I would have moved my sewing machine and stuff upstairs to give you more room if you would have asked me". Queen of the after-the-fact statements, that's my wife. Anyway, there will be no switch to HO. I am settled into N scale and don't mind the tinyness of it anymore. But.....if that railroad needs to expand in the future...I think I know who can be reminded of one of her after-the-fact statements.