Normal street driving on belter hot days, the highest I've seen in either car was 95deg, nothing to worry about.
The 32, on a 40+ day and a good 2 min skid, the highest I've seen is 105deg which was fkn hot but still didn't throw any coolant.
Coolant, under pressure, isn't going to boil until about 110deg. If you're seeing about 100deg or higher on the street or highway, then you've got issues that need addressed.
From my experience, RB's like to operate at about 80deg (RB20/25non-neo/26), they run a 76.5deg thermostat. The neos seem to want to run a bit hotter (probably due to emissions reasons) and they run an 82deg thermostat.
Edit: I also had way better results from a stock GTR radiator than the 50mm chinese alloy thing I used to have.