I have a shortlist of stuff I'd love to see ^^
1: As you guys have both said, a new chapter or set of chapters for Jill to give her more screentime and show the story from her prospective.
2: More unlockable costumes, but the costumes should be tied to online play, from a mercs mode SS duo rank to defeat X players in survivor mode....Jill's STARS outfit should be included for definate!
3: Jill unlockable as a playable maingame character (can be swapped with Chris and Sheva through bonus features) put it as a difficult achievement however (obtain x amount of S ranks on professional)
4: More characters added to mercs mode, likely candidates are Barry Burton, Hunk, Claire, Leon and Ada, each requires unlocking, but HUNK would be the most challenging.
5: More maps to play on through mercs mode, a large sniper-friendly map like the ship would be welcomed ^^
6: Balancing of current mercs characters, Weskers Cobra strike taking a hit to critical percent, STARS Wesker losing the hydra but getting a jailbreaker in its place (the hydra given to STARS Chris instead of the horrible mg), A heavy hitting weapon given to both BSAA Jill and Clubbin' Sheva, infinite ammo taken off of Tribal sheva's longbow and arrows dropped in quivers of 6 and 12 (much like Krauser in RE4)
7: Global leaderboard reset, better monitoring of Melee "sploiters" and subsequent removal from the leaderboards if they are exploiting a characters "bugged melee" to wrack up an insane score (wont be a problem if a cobra strike nerf is implemented)
8: Reaper insta-deathblow from behind removed, or the frequency from it triggering when behind a player substantially lowered.
9: Proper ending implemented to main story, the ending was terrible, unthoughtful and poorly implemented....real one please!
just my 2 cents on what needs to be done to improve the RE5 experience through DLC