Praia, the capital of Cabo Verde, is located on Santiago. Then there is the already mentioned Cidade Velha and a beach resort in the far north of the island. These are the reasons why the few tourists are visiting Santiago.
The interior of Santiago is quite pretty, very mountainous and quite green (it was end of the dry season, therefore it was often more yellow...). All the same tourists do not come for landscape.....
Praia is quite nice for one or two days, quite "african" compared to other places, has quite a few hotels of all categories, restaurants and cafes for local cuisine. I do not want to miss the experience, but two days in the city was enough. However it is a good base for exploring the southern half of the island.