  We construct smooth bundles with base and fiber products of two spheres whose
total spaces have non-vanishing $\hat{A}$-genus. We then use these bundles to
locate non-trivial rational homotopy groups of spaces of Riemannian metrics
with lower curvature bounds for all Spin-manifolds of dimension six or at least
ten which admit such a metric and are a connected sum of some manifold and $S^n
\times S^n$ or $S^n \times S^{n+1}$, respectively. We also construct manifolds
$M$ whose spaces of Riemannian metrics of positive scalar curvature have
homotopy groups that contain elements of infinite order which lie in the image
of the orbit map induced by the push-forward action of the diffeomorphism group
of $M$.
