General Santos, Mindanao would not be the first destination of choice for the vast majority of Filipino or foreign tourists. Its claim to fame is probably its tuna fishing and canneries.
Having said that, my recent visit gave me the impression that to a small extent at least, this quite reasonable sized smaller city may be about to awaken a little more from its tourism slumber.
The existing range of hotels or other accommodation is not stunning, but I gather that three new hotels are under construction. This is usually a good sign as hoteliers do their research and try not to simply be altruists.
The city is safe, as are the areas on either side, at least for 40 kilometres north and 60 kilometres south as I travelled. The three malls (elderly Gaisano, newer KCC and quite new Robinsons) are about to be joined in a month or so by a decent sized SM City (which would have Robinsons worried I imagine).
I found one decent nipa hut themed resort 55 kilometres south of the city: see my TA reviews for the town of Glan.
GenSan won't be the next Boracay, but it may slowly attract a few more tourists especially given the convenient Cebu Pacific flight times and the efforts of other carriers such as Airphilexpress to link GenSan by air to both Mactan Airport, Cebu and growing Iloilo, Panay.