Traders should be able to open businesses in the cities apart from the Plazas. For those of great accomplishments, perhaps they could obtain a stall or a stand to begin with. As they grow, so will availability to larger structures such as tents or yurts. Larger 'shops' could include shops and storefronts and may include specific businesses like pizza shops, restaurants, general shops, and crafted wares. Access to these type storefronts may need a higher level to obtain. I also see access to rare and unusual items at a wholesale price. I could go on for days but I think you catch the drift.
Thanx X