SQL Availability Group and SSRS, SSIS and SSAS
I am thinking where to install my SSIS / SSRS / SSAS.


If it were me, and I was the one having to administrate the servers, I'd load these each on their own individual server with their own individual resources. Virtual servers are great for this, and if you aren't sure about the load then it is very easy to adjust resources.

When I see servers that have everything loaded on them and all running - I know there's going to be a problem, it's a matter of when and not if.


  If they don't have high availability requirement, then does it make sense to install them on node 2?


If you're into that sort of thing, then sure by all means. If you're limited by some other reason, then I would fight for more of whatever resource you are low on... disk, servers, memory, licensing, etc., as 15k for a new server is generally less money than 1,000 work hours wasted by everyone troubleshooting issues.


  The only draw back I see is the potential network congestion.


Here are a few more for the list:


None of the services know about each other
This can severely impact your FCI RTO
"Phantom" performance issues
Non-Scalable setup
Overly complicated troubleshooting (as a result of #3)


Don't get me wrong, in a pinch this can absolutely be done and sometimes when the servers are beefy enough and the load is small enough and not so important that a few hiccups here and there will be noticed then it can work.

For example, a runaway/poorly written/large data SSIS package is running but it's slow - what do you troubleshoot? Is there also a large parallel query taking up CPU in SQL Server, maybe the SSRS report is running a large report and rendering, at the same time SSAS is rebuilding a cube. How do you show that one is impacting the other?

With all of the services running on the same server, it's extremely hard to pinpoint individual items... it can be done, with the proper amount of monitoring and troubleshooting. However, as stated before, I'd rather have each isolated so that when this inevitably occurs, I can get to the root of the issue much faster and with greater accuracy.


  My understanding the active node will be the one taking most of the load so that's why I think to install the other stuff on the passive


I wouldn't continue thinking this way as you're setting yourself up for more issues. Instead, think of AGs and FCIs as "running anywhere, I don't really care" and your designs will be much more robust with less overall issues. Assuming that a single server will always hold a service on it in a WSFC is a bad assumption. Assume it will be on any of the possible owners at any given point in time.