I am afraid I am going to be of limited help here as I am an electrical engineer in the UK but I will do my best. My company lets me try anything I fancy but actually buying the plug-ins.... not so much.
I have used Trimble (formerly Amtech) ProDesign 3D. This moves the cable sizing calculations from a separate software package to reside within Revit. When I create a circuit in Revit it will then allow me to calculate and document it without having to move all the details for the circuit into a separate package, I liked this very much. Now we have the Edit Path tool to sort out the length of the circuit so it is measured correctly this is a must-have for electrical engineers, unfortunately it is prohibitively expensive, they are really missing a trick here as nobody is going to buy it at the price they are asking, no matter how good it is. They are focussed on the up-front sale income rather than the on-going maintenance income, a rookie mistake imo.
I have also used the Elumtools trial, this was before they added external lighting and emergency lighting calculations. Another no-brainer and its not even that expensive.
We would really like MagiCAD for mechanical design calculations, we've had the sales demo's and have talked to some actual users, seems to be just what we need as Revit's native design calculations for pipes and ducts are no use for the UK market and can be a bit flakey. Very low flow values for pipes default to a higher than normal minimum value so it doesn't calculate properly using the in-built revit calculation engine. I'm sure this will get fixed eventually if it has not already.
I think MAgiCAD would be a replacement for most or all of Carrier HAP, not sure if it works with USA standards or not, I think it may do. The chap who is leading the mechanical development of it is a pretty smart cookie so the software is similarly pretty awesome. Not perfect but nothing is.
We use xRevTransmit to print drawings, this paid for itself in about 4 minutes. Super awesome tool, definitely go buy this as it's cheap.
Please go and find the people who say not to use spaces and boil them in oil, perhaps twice, just to make sure they know how silly they are being.
Architect's use Rooms, MEP folk use Spaces, they are custom designed to make out lives easy and store huge amounts of useful information. They drive a lot of automation that saves time and reduces inaccuracies in documentation and scheduling. The automatic space creation and naming tools that are native in Revit make using them really easy.
TBH you need to get hold of somebody who has more experience to lead the way, Spaces are way down the list of the complexities of Revit and the lack of expertise will be why your efforts are failing.
You want to try and swap the excel spreadsheets for revit schedules wherever you can. This will require changes to your workflows, formatting and company standards but it will pay back in time saved and ease of use.
Most of the benefits with Revit come because you have to produce the drawing anyway so why not get all the schedules etc for free as a nice by-product. When you start buying your QS and PM team in accurate quantity schedules they generally start to buy into it as it saves them weeks of time on every project.
This all requires the model to be good quality, you live and die by the accuracy of your drawings.
I hope this helps.
