On my layout, I used thevery broad selection of sectional GarGraves curves. To make the curves appear more realistic I transitioned from larger-smaller-larger. Example, 063, 072, 080, 089, 096, and 106 are all 12 sections per circle. A combination of 072-063-072 render a 90 degree turn. Mixing sizes break up the symmetrical circular look.
The flex is great when you are "here" and want to go "there". Start at one end and just work your way down the length until to you've achieved the desired curve, offset, or whatever. The only "trick" is to cut the track ends square when you're done. You can also make a plywood template to make any alternate diameter you need to make things work, ex: 43.5".
My advice, buy a piece of GarGraves flex and play with it. The worst you can do is trash one piece of track. I think you'll find it both useful and easy to work with.
