Likewise, I just got back from HD and measured the floor model. Here's what they have displayed to the world...
Nice job, boys. Yup, just like Weber designed it and intended for it to be used! Anyway...
The outside-to-outside of the lip is 18 7/8" on both the 14' and my 13' (both units were measured for roundness and within 1/16")
The inside-to-inside of the body was 17 3/4" on the 14' and 17 7/8" on my 13'
The support straps appeared to project 1/2" on my 13' and measured 16 7/8" inbetween them. For obvious reasons, I couldn't measure the 14'
The cooking grate measured 17 1/2" on the 14 and 17 7/16" on my 13'
If I rotate the cooking grate on my 13', I can see where things would be close to having the opposite support not under the grate. I think mine would be supported by 1/8" at most and that's to a rounded cooking grate on a body which isn't supported to stay in 'round'
I haven't had an issue yet, but I also (subconsciously) place the cooking grated centered on the supports when I place it it.
From what I'm seeing, I don't see any changes from the 13' to 14' model years in regards to measurements.
Actually, the 14' measurements on the display unit make more sense with a slightly tighter body and a hair bigger grate.