Just like the ice cream, the interest in vanilla is in the details and qualify of crafting it. Pick up a tub of Breyer'sstore-brand vanilla, then compare it to a small-batch local gelateria's vaniglia — there's a huge difference.
So too, in campaign settings. Making the big, broad strokes of the setting "weird" or unusual is the easy, superficial way of making the setting interesting to the GM (much like novelty flavours of ice cream), but hardly the only way. And just like "interesting" flavours of ice cream are only so-so without paying attention to their details and craft, even unusual settings thrive or die on the quality of their details.
Focus on the details
Bog-standard fantasy settings can be quite interesting, if you start looking at the details. Zoom in. Focus on cultural details, the familial relationships of powerful clans (because familial = political at that scale). Toy with border conflicts, dig into the ideologies of religions, investigate the motivations of the poor and the rich. Ask questions about the economic relationships.
Look for where there is vulnerability, imbalance, or cracks. Push there. See what insights you can derive from them. Add more stresses and fractures. See where power blocs lie, where stability resides at large scales. See where there are alliances and enmities. Investigate the internal stresses and balances of them. Ask yourself how they might change.
Then show the details, don't tell
Bog-standard fantasy is a convenient canvas, which you can leverage to quickly get on the same page with your players. They immediately have a grasp of how the world works. As they explore, present something in the world that reveals the details that you find interesting, get them entangled more in the parts that they respond to. Reveal the vulnerabilities and strengths of the world and its inhabitants, and observe what your players do with those. Do they ally with the powerful and stable? Do they exploit the vulnerabilities? Do they leverage cracks for good, for evil — or just for their own neutral gain? Do they become playmakers, or are they satisfied to be playing pieces in larger events?
Zoom in. The interest is always in the details. That's even true of stranger settings, but it's never so starkly obvious where the real work of a GM is, than when you're running vanilla fantasy.