NPM and NTA are server applications designed to be setup in a single environment and ran continuously for years.
If you are looking for a laptop application(s) for going from one site to another diagnosing problems I would recommend you take a look at the SolarWinds Engineers Toolset. It has a lot of the functionality you will find in NPM and NTA but is more designed as a desktop/laptop application for situations like you are talking about here. You could also check out some of the SolarWinds free tools for this as well.
The Engineers Toolset really is a toolbox of different monitoring and troubleshooting software, you have a bunch of real-time monitoring tools as well as things like Switch Port mappers and Port Scanners.
Hope this helps!
That is the prefect answer actually. Thank you very much. Already downloaded the Toolset, I'll give it a go this afternoon.