Wow, those are some nice finds! Here's another:

$238 DCA-SRQ (Sarasota, FL) 3324mi LAA00AZN
Tue 4 Nov
UA3549/1190 DCA-ORD-SRQ 0605-1209
UA1179/620 SRQ-ORD-DCA 1259-1849

SRQ connects only via ORD (on UA/UX), so it's a good one to keep in mind to get some extra mileage.

EDIT: You should keep in mind that mileage doesn't post for about 48 hours, so a trip on Nov 4 will typically post the evening of Nov 6. So hopefully, this is factored in on your dates requested. If not, skyemma's suggestion of DFW is interesting, as I still see it available for this Sunday (Nov 2) for that price! EDIT #2: sorry, I missed that your next flight is next weekend. So mileage should post before T-24 check-in time. Good luck!