Class A, B and C is a broker classification, and there's no standards body that issues it. It's relative to the local market, so a Class A building in a small metro can be older and smaller than a Class B tower in a large one. Your broker calling a 1998 building with a fountain Class A isn't wrong in his market, it just isn't portable.
"Prime" as the research houses use it is stricter. It means the best space in that specific market, usually recently built or heavily renovated, well located, with the amenities and floorplate flexibility that occupiers are actually competing for, and it typically sits at the top of the market's rent range. When you read that prime space is getting scarcer, that's a small pool of specific buildings, not everything a listing sheet labels A. The loose usage treats prime and Class A as synonyms, and that's where people get in trouble comparing markets.
On the lease structures, they're two ways of dividing the same bill. Full service gross means the quoted rent includes operating expenses, so at $26 full service the landlord pays taxes, insurance, utilities and cleaning out of that $26. Triple net, written NNN, means the tenant pays those separately, so $18 plus $9 estimated is about $27 to the tenant. Your friend's point applies to the tenant, who can question the CAM reconciliation. As landlord, NNN is what protects you from expense inflation, because in a gross lease a jump in taxes or insurance comes straight out of your NOI.
One thing to ask for on any lease you look at: free rent months and the tenant improvement allowance. A $26 rent with eight months free and $60/sf of TI is a much lower number than $26 once you spread it over the term.
