Anyone ever taken this on and have any advice? Looking to do storage on the bottom, with shelves on top. Nothing too crazy. Wall is ~12.5' wide x 10'h. Looking into doing one of the ikea billy bookcase hack type installs. Just beginning to look into this so any advice/thoughts would help! I am moderately handy, but never taken on a project quite this size. Thanks!

2nd part of the question - is there something better than google sketchup that people are using nowadays to plan projects? It's been a while but that is what I used last time.

Sketchup is not google anymore. But still works for these things, and still has available free tier. I typically use fusion 360 who also has a free tier but if you are familiar with sketchup i would stick with it
Other options are freecad or even SOLIDWORKS through something like eaa non commercial license

I use a pencil, ruler, and paper. it seems to work very well.

Where are you located? I built all of the cabinets and builtins in my house, so I am happy to chat if you have questions about building or installing.