We can run telemetry experiments that send back urls of whitelisted sites to get a sense of what type of traffic to expect on enhanced tiles. We have the experiment code in bug 1062708, and we'll want other bugs to track the analysis of those results.
Bug 1108489 is only for stats on which sites are more popular. Do we want to also generate stats on pairs of related sites? E.g., site A shows up often with site B?