Layout Expansion

I am considering expanding my layout to enable running of more than one locomotive at a time. Layout is a modified phone booth design 6X10. Keep in mind this is to continue to be a grandkid friendly operation. Current layout was put together when I pulled out all my old O27 stuff from the late ‘50’s……Lionel 2055 and Erie 610, track, switches, a few accessories and various rolling stock of the period. I did pick up an RMT Bang some time ago and that has seen some run time as well. Power is a 275 ZW and for me I prefer to operate conventionally.
I want to retain for nostalgic reasons some vestige of the old O27. That being said I would also like to venture into some more modern stuff particularly Lionel LC Plus. My feeling is that this will offer more “play value” for the grandkids especially with the remote for control while retaining the semi scale I currently have.
I have been playing with Anyrail software (have not figured out how to fill gaps ). With the expansion I am essentially adding a connected outer loop with O42 curves/switches. As well I am modifying an inner loop with O31 curves/switches while maintaining most of the figure 8 entrance and exit O27. I plan to add a 1’ to the perimeter for a table of 8X12. This will fit the area with access from all sides so I am comfortable that would all work. Below is what I am considering.
So, I would be interested in your comments from 'your nuts' to 'get ‘r done'.
Ken