To be candid, if I was in your situation, I'd run each pair of speakers (sub and top) to one circuit on the spider box (you have 6 circuits available). Then one circuit does stage power/backline, and one does FOH and your two wedges. That's going to balance everything really nicely over the available circuits on the spider box.
(I typically see spider box outlets wired X then Y then X then etc -- so the first Edison you find is on the X leg of the incoming service, and the very next one to your right is on Y, and then X, etc. So, you can use that pattern to make sure you're splitting everything between the two legs of the 50A service from the generator. Metering hot to hot should read 220v, thus allowing you to verify that pattern.)
If it's a 25kW generator, upstream breaker should be 60A, so you'll be fine.
As noted, make sure everything meters properly before the electrician leaves! Some newer generators have a "low engine speed" switch- if you're reading 60V or something scary like that, where you're expecting 120V, that's usually the issue.
-Ray