I started thinking if there was a quest line where not only could you make choices that wouldn't affect the lore but you could continue to enjoy it after you'd completed it.
My idea is in a city you have 2 shopping districts. One where all the rich folks go. Everything would be expensive, there'd be the high level swords and armour sets, unique clothing and jewellery. There would be guards in every shop to prevent thieves and it would generally be a nice area.
The 2nd area would be more of a downtrodden market with stalls on the side of the road. They sell cheaper produce with the odd rare item at a cheaper price than the rich market but they also buy and sell on your stolen goods.
My line of thinking was both of these shopping districts have different groups running them each of whom are striving to get rid of the competition. You choose whether you want to work for the poor district or the rich district and after a series of quests requiring sabotage on your opponent, to going to x location and acquiring x item for one of the shops. On completion of the quest line you are given your very own shop in the district that you chose to work for.
It is then your job to keep your shop filled with items that you can sell. If you work for the rich district then you can only sell items that you have picked up legitimately through adventuring and you would still have to go to the lower class market to sell your stolen items but if you chose to help the lower class market you can sell stolen items on your stall although any rare and expensive items you pick up you'll struggle to sell for much in your shop as the customers you attract don't have as much money.
If this has already been suggested I apologise and any improvements on my idea would be welcome.