More Localised Anomalies?
How about this.
Announce 9-15 sites each series. Well spread out ones across the 3 larger zones. Do the whole pay for the badge as long as no work or assistance is required from agents.
Score each site based on attendance of the smaller faction. Eg. A site gets 50 Res & 50 enl, it's worth 1 pt. A site gets 150 Res & 50 enl, it's also worth 1 pt. A site gets 200 Res & 200 enl, it's worth 4 pts. If a site gets 10 Res & 50 enl, it's worth 0 points. And everyone checked in on ground gets the badge regardless of site attendance.
It'll keep anomalies within reach of more agents by requiring less travel, smaller per site attendances. At the same time you'll see bigger overall attendance and improved competitiveness with other otherwise large numbers being split up better. At this point you have enough data from FS & Hexathlons to figure 45-60 cities for rotation in each zone (Americas, EMEA & APAC) and the numbers they can get.
The Hexathlons are lame. You're not going to get people to bother about them. They're just not what Ingress is about. Even the badges for those are so weird (who gives a worse badge to the top participants?). If you want Ingress to survive you need more anomalies.