Food for Thought
The BB&B is a freight set. A beginner too. The only set cheeper is a Thomas for 169. It must be an exclusive set, because it is noy listed in the Lionel catalog. I have heard target has a set too.
The recommended age is 8. One good thing is the track is interlocking and it comes with a transformer. As with any toy ,supervision is needed along with some play rules. The area is 40 by 60 inches.
The set is not cheep you could find something in Ho with the easy track and transformer, and save some there. The area needed will be smaller. The parts are smaller and tend to fall apart easier than Lionel.
If you use a table you will need some type of guards to keep it from flying off the table . It will not last long like that, or keep it on the floor.
Children like fast trains.
The cars are plastic and will only take so much abuse. Otherwise it will fit around the tree.
The only other thing I would suggest is to get a diesel engine instead of a steamer. Easier to remove the top to oil and there are no side rods that bend or get in the way. The smoke unit is another complication for a child.
With the way prices are you could buy another set if you are interested in just getting a diesel.
With the right approach you can make the boys realise it is more than a toy and needs to be care for if it is to last.
Hope this helps