1. A beefed-up marriage system. ie: a little more depth to marriage once you're married, and hopefully a little more "romance" or dialogue, maybe questiness, leading up to it. (At least for some of the options, if not all). Being able to marry certain key people have have it affect the game in some way, for instance, would be awesome.
2. More marriage options. Have all the race/gender combinations represented at least, and preferably a few "types" in each race. Sooo tired of almost all the husbands being big beefy and/or facial-haired types.
3. I really like the fortress/maybe small village idea. Let it take some questing or something at least slightly difficult to get, but once you have it, you can send the various possible followers there (once you get them/hire them/whatever) so that you can just switch them in and out there. Let us put the various crafting stations there. And if you're married, your spouse's store could get more intricate and beefier. And yeah, let us have options of how to decorate, rather than just a few upgrades that we either have to buy or not. Maybe it could even have a stable so we could buy multiple horses, and switch out between them.
4. The ability to craft your own custom spells again would be nice.
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Edit: oh yes, and how could I forget?
5. Add at least one more ring slot for Ysmir's sake!