I use a mid-2012 MBP retina (2.3GHz i7), and I would second what @davidheim1 wrote, even though this isn’t the latest and greatest. I haven’t tried a gigantic model, but have no issues with performance on the things I do (mostly woodworking). The thing to look closely at on the other models is the graphics processor. The built-in Intel graphics are reported to be marginal for SketchUp. NVidia are much better.
The thin line, etc. issues are shared with all high-dpi displays, including the iMac 5k and recently released 4k Windows laptops. The custom menus and on-view text used by some extensions (notably those by Fredo6) are so small they are almost unreadable. A workaround is to enable Zoom under the Accessibility preferences, which will let you zoom up just the part of the screen containing those menus while you read and make choices on them. There is also a suite of increased size inference engine markers available (search on sketchUcation) that make the snaps a lot easier to see.