mille395
Hello & Welcome to the Forum!

I can't add much to the information TrainLarry has already given you.

There is a very large contingent of us tubular track aficionado's out here
running our trains the way a Toy Train is supposed to be run, on tubular track!
You can get O27 tubular track or O tubular track which has a larger variety of curve radii.
Don't be snobbish about used tubular track. If its been cleaned well and tight, it should serve
quite sufficiently. If they're not going to be located where they're difficult to reach, used manual
switches for tubular track are readily available & reasonably priced.
Some of the track that I uses is 75+ years old. The rust & accumulated dirt/dust
I see as Natural Weathering.....

Happy Rails!
Dave