One of the things I really like about the movies is that they don't have any obvious size changes. I never liked that Megatron turned into a gun yet stood as tall as Starscream. I just don't like size changing. So with that in mind, I have a dream that some day I will create an entire series of figures that are completely in scale with each other. I have no idea what generation it would be or anything yet. This is currently just a pipe dream as I lack the skills and resources to do this. But man, it would be really cool to me. Just wanted to share.
I think your best bet would be to try and focus on Cybertronian vehicle designs - be they WFC, movie protoforms, or just otherworldlyu/futuristic designs from A/E/C. The great thing about made-up vehicles is that they can be exactly as large in relation to each other as you want.
Build a 10 foot tall city-bot such as Metroplex, and then collect all the WST figures. That would be your best bet. Good luck whatever you do.
But that's kind of cheating isn't it? I mean the point of doing everything to scale is for them to be different sizes. But if I do Cybertronian style then their sizes are moot.
