I also recommend the Dell Precision series for running SketchUp.
Without spouting a lot of technical specifications, I will say that I have used 5 different Dell Precision Workstation laptop machines over the last ten years or so and I have been very satisfied with the performance of each. In addition to running SU on them, I have made use of AutoCad, ArchiCAD, Vectorworks, Revit, Photoshop, Acrobat, various renderers, various video creation software packages, MS Project and the MS Office suite. I typically will have several of these programs operating simultaneously, just like any other power user, and have had very few issues over the years.
The only drawback i can point out is that, with the exception of my latest Dell, the Precision series is usually a bit heavier than many of its competitors. It has exceptional battery life, can be configured to have very large memory capacity, is quite fast and is just a joy to use.
Here is a link to the most recent iteration of the Dell Precision. This unit has a 17 inch screen…there are other models that have smaller screens and weigh less, but the larger screen is always my preference.
CLICK HERE FOR A LINK TO DELL PRECISION INFO
Personally, I strongly recommend this Precision series as it was designed specifically to be used by engineers and architects. An added plus, is their warranty coverage. My systems all have coverage that repairs or replaces any problem by the next business day.