VBOs with std::vector

If you have a std::vector<T> v, you may obtain a T* pointing to the start of the contiguous data (which is what OpenGL is after) with the expression &v[0].

In your case, this means passing a Vertex* to glBufferData:

glBufferData(
   GL_ARRAY_BUFFER,
   vertices.size() * sizeof(Vertex),
   &vertices[0],
   GL_STATIC_DRAW
);

Or like this, which is the same:

glBufferData(
   GL_ARRAY_BUFFER,
   vertices.size() * sizeof(Vertex),
   &vertices.front(),
   GL_STATIC_DRAW
);

You can rely on implicit conversion from Vertex* to void const* here; that should not pose a problem.