I have an LGB starter loco and 9 cars that I have had set up at Christmas since 1985. It's been through 3 eras of kiddies in the family. I never had any "rules" about how to play with it. I had to replace the motor about 10 years ago. One of the kids thought it was fun to throw it in reverse at full speed.
Other than a few broken minor pieces and the motor, it has held up nicely. I have it in the original boxes and it looks nice. I use LGB brass track 1600 size curves and straights make an oval of about 6x12 feet. I use a track brightener (kinda like an eraser) to clean the track when I set it up and it's good for the month it is running.
There are about 5-6 scales that use their G gauge track. From 1/22 to about 1/32. Several different manufacturers make nice stuff. They take a lot of room to have a nice layout, that's why most are outdoors.
Good luck with whatever you decide.