Cross domain, Cross site traffic analysis - Best Practice?

[#1]

I'm in the beginning steps of gathering data & insights regarding visitors to a few of our sites. I'll try to explain the situation the best I can for a No0b:

• We have 3 main sites, each with their own report suite. I also have a rollup suite that includes these sites (plus one other).
• I have an eVar on each site (plus the rollup) that captures the Experience Cloud Visit ID. I'm using the same eVar number in each if that matters.
• Each site receives a large amount of traffic per month; millions of visits each. If the volume was less, I would simply export all traffic with the needed data fields from each site into Excel or PowerBI and do a quick Venn or Crosstab to report on the overlap using Visitor ID as a "primary key" of sorts.

I'm sure that we have visitors that go to all three sites in their purchase journey. Not only would I like to know the number of cross-site visitors to each site, but I'd also like to know a bit more about this journey.

My question: What have you found to be best practice or your preferred way to identify these visitors in the rollup suite; while still being able to report WHICH site they traveled to and from? This seems like a simple request; I think I may be overthinking it or missing a step. Either way, thanks so much for the help and advice!

[#2]

This may not be the answer you want, but I use a global suite for my sites, then use Virtual Suites to break down the traffic per site....

However, being on a Global suite, with all sites being "internal" traffic, I set up pathing on the "site name" value to see if users were moving from Site A to Site B (but I also make sure that the site name is part of the pageName so it comes through in the standard pathing report) - this is because Site A won't be a referrer to Site B, or vice versa.... 

[ptrost]

The rollup report suites can't help with the cross-report suite data analysis.

[ptrost]

Thanks Andrey (love your videos on YouTube). What might your strategy be if you were in my shoes? We don't currently have Analytics Ultimate, so any option related to Journey IQ or CDA may not be possible. Am I on the right path using the Experience Visitor ID to identify these visitors? I attempted to use Data Warehouse to pull data into PowerBI or Excel and failed, perhaps I'm trying to extract too much data for this purpose. Am I missing something basic? Thanks again Andrey!

[Andrey_Osadchuk]

If I were in your shoes :), I would begin the implementation upgrade to multi-suite tagging to add a global report suite the data is captured to from all existing websites. Yes, the Experience Cloud ID is the key, you are on the right path. If the DW reports fail, consider daily run (rather than weekly/monthly) to reduce the amount of exported data. If it does not help, contact Customer Care. Also consider raw data export via Data Feeds if you can process it on your backend.