I guess I'll keep updating this even though my replies aren't showing up...
Goldilocks is very cool for determining which textures need love. Should be adopted by SketchUp as a standard tool, brilliant idea from whoever developed it.
Unfortunately, giving those textures love is proving to be extremely convoluted.
Can't get "Texture Resizer" to work. Even with a working copy of ImageMagick, it's a dead end.
Also, SketchUp's "edit texture in external image editor" function is broken for a lot of SU2015 users, myself included. Followed that rabbit hole for a couple hours and gave up. Other users with the same issue never posted solutions. Now I have to export .dae with texture folder, find the offending texture, edit in Photoshop, reimport the texture after deleting the old one and purging, resize and place the texture everywhere it occurs in the model... it's a 45 minute operation in some cases, and when I'm done I still have to check Goldilocks to see how well I did, and perhaps go through it again.
I guess I was expecting more after being away for a few years. Getting textures to play nice with SketchUp shouldn't be so difficult.