Saudi Arabia is in a good location for logistics and transshipment hubs (although this is something else they've probably lost to Dubai). There's also obvious tourism appeal, due to the historic sites in the Hejaz (probably already maxed out though, unless they want to open it up to non-Muslims). The other obvious choice for a commodities producer is to move up the value chain: go from selling crude oil to selling petroleum-based products instead.

The biggest issue is the effect that the resource curse on the workforce, as you note. There is a small contingent of well-educated Saudis (largely found in Saudi Aramco), and the country has instead relied largely on giving their population sinecures in the government, which hasn't exactly done wonders for productivity.