Like Grits, I would most like to see consequences for your actions return to the series. The only one Aedric/Daedric artifact that Vital pointed out sounds like an excellent idea.
I would like to extend that to only being able to be in one Guild at a time, as well as making joining a Guild something that takes both effort and aptitude. Back in Morrowind there were minimum skill values you had to possess to join and advance in Guilds, that would be a good start. I think the Guild quests ought be built in such a way that you need the appropriate skills to finish them as well. For example a Thieves Guild quest should have locks you need to pick to complete it, a Mages Guild quest should require certain spells, a Fighters Guild quest should have challenges that involve defeating opponents without using spells, and so on. If you can't hack it, then you have to leave and learn that spell, get your lockpicking skill up, and so on.
I would also like to see Guild rivalries return, at least making people from diametrically opposing Guilds such as the Fighters and Thieves Guilds dislike each other. It would probably cause too much chaos if the "official" guilds like Fighters and Mages attacked one another on sight. Though Skyrim does have members of the Assassins Guild attacking your character on sight... But Grit's suggestion of a vampire having Boeithah cultists attacking them sounds great. Or a priest of Akray having necromancers come after them.
That folds into having religions that you can choose. The thing there however is that Tamriel is presented as a polytheistic place, so a person following only one deity would seem odd to me. Following the Nine however sounds perfect though, and being able to invest most of your time with one of the Divines sounds good - not the total exclusion of the other eight - just a focus on one. Since the Daedra don't seem to play that well with one another, that might work as an only one Daedric Lord. Or perhaps only a certain number (like three if you are a 4th Age Dunmer believing in the Reclamations) of non-opposing Daedra. I also think you should be able to choose an agnostic or undecided yet religion, as well as plain old atheism (its all just some magic-using clerics faking it in order to gain power and wealth after all...)
Interacting with things like altars of your religion might give you a larger bonus than undecided people. Interacting with opposing religion's altars might cause damage or curses. Likewise with interacting with people belonging to the same or other religions. There might even be a few unique spells that can only be learned by members of the same religion, like an Arkay's Wrath spell that damages only undead.
Basically I would like to see truly unique opportunities
and penalties open up in the game depending upon the choices you make for your character. So no two games are the same, and you cannot do everything with a single character. Unfortunately that latter is exactly what Bethesda wants.
This post has been edited by SubRosa: Mar 27 2014, 11:06 PM