I'm new to this forum, but not new to Lionel Trains. I've had my train for 58 years. I've always set mine up left it for a while, then taken it down. I've had it on a 4x8 table, which is too small. Now that I'm older and close to retirement, I have the room for a larger set up. Plus with a grandson coming, I'll have someone to pass down my trains to.
My thoughts are, you can never have enough space, and what ever I build, it'll probably be too small after I get started. I was looking at building 2 tables, with folding legs (in case I need to take down and move if we need the basement for other family activities). Each of the tables would be either 5' x 5', or 6' x 6'. I have the space for about 6' x 12' max.
With having 027 trains, and young operators, I was also thinking of building a table with some sides on it to protect the train if there is a derailment.
I haven't given too much thought to how I want to layout the tracks yet. I'm more focused on the table size, and how to make the table so that it could be moved. I do have 5 engines, plus cars, a lot of switches. More remote than manual, and a ton of track. I'm thinking of multi level layout so I can use my trestle's in the layout.
I just purchased a complete setup from an estate, and got 15 remote switches, buildings, 2 sets of engines, and a ZW transformer, so I have plenty of hardware to work with.