O-Ringen looks fun next year in Ornskoldsvik. That might be a good July option.
Also, the week of California races at the end of March, though not European, is nonetheless tempting.
As for sublime terrain, it's hard to beat the Slovenian events: OrienteeringOnline Cup and Bubo Cup, usually held in the second half of July.
Finally, besides the obvious WOC, there is also a week of European Champs/World Cup races in Switzerland in May that looks fun.
(And clearly you should do Tiomila or Jukola. I think the time is ripe for COC to field a team!)
Bubo Cup is definitely on my list - strangely enough I haven´t done it yet...
Sadly I suspect the logistics for a Cascade team are prohibitive.
I'd be down to do some of those with you this summer if your thinking about 2018.
Yaaaaassss! Graeme and Will's Excellent Adventure.