Hi there! I'm also primeideal on Ao3. I wrote a couple treats for the original run of the exchange and was invited to leave prompts in case this inspires anyone else. Feel free to use as little or as much as this as is helpful.
Things that would be fun to see for any ship: happy endings, sad endings (when providing some measure of closure or melodrama--I'm fine with character death), nonstandard formats (documentation, epistolary, "Backstroke of the West," "William Shakespeare's Star Wars," verse), time travel, five things, canon-divergence AUs
General dislikes: ambiguous endings, issue-fic, explicit sex, underage sex, rape/non-con. If something relies on knowledge of secondary canon, I'm afraid I probably won't understand the allusions. I prefer no AUs that are mundane in the sense of humdrum, but if you have an idea for these ships that brings out the fantastic and hopeful themes of Star Wars in somewhere equally dramatic but a different setting, feel free to go crazy. And while I like most unconventional fic formats I'm not a big fan of plain second-person prose.
-Alderaanian worldbuilding! How they fell in love in happier days before the empire.
-Fake-fake dating trope subversion; they're already married, but they still need to keep their rebellion affiliation undercover.
-Leia's Force powers manifest at an inconvenient time. The cover-up is awkward.
-Finn is embarrassed by his legendary status among the growing ranks of subversive/defecting stormtroopers. Rey thinks it's adorable.
-Finn is terrified of being "reformatted" back to FN-2187 and asks Rey to kill him rather than let him be taken alive if it comes to that. Does she fail, follow through, or do they find another way out?
-Something transplanting the dynamic of them fighting in different ways, but always watching each other's back, to another setting.
-They don't understand how each other could be so incredibly wrong about some subjective point of spacecraft comparison and get into stupidly petty arguments about it.
-BB-8 decides that if Poe keeps losing terribly at sabacc, it's time to take matters into its own digits and find an algorithm to help turn the tables.
-Poe draws the short straw and has to tell Lando about Han's death.
-Luke sarcastically asked for a droid who could speed up time and get him off Tatooine. Little did he know that Owen and Beru had purchased a time-travelling droid in C-3PO. Life is about to get interesting.
-An AU where they raise Leia and/or Bail and Breha raise Luke/some other permutation in the twins' upbringings.
-Outsider POV on the events of the prequel trilogy (or vice versa, other prequel-trilogy characters' POV on their relationship).
Again, no obligation to use any of this, just on the chance it sparks your interest. Anything about these ships would be cool to see. May the force be with you! :)