rt.representation theory - Interesting representations/cohomology of surface groups?

For purposes of my own, I'm interested in constructing connected spaces, without recourse to geometric realisation or the like, that have non-trivial homotopy groups in dimension 1 and 2 and are not products of Eilenberg-MacLane spaces. This rules out obvious constructions using crossed modules (at least, obvious to me).

One idea is this: take a representation $rho:Gamma_g to SO(3)$ of $Gamma_g = pi_1(Sigma_g)$, the fundamental group of a compact, connected, orientable surface or genus $g$. Then form the associated sphere bundle $X=widetilde{Sigma_g} times_rho S^2 to Sigma_g$.

Then, unless my calculation is wrong, $X$ is a 2-type space with $pi_2(X) = mathbb{Z}$, $pi_1(X) = Gamma_g$ and $k$-invariant $ain H^3(Gamma_g,mathbb{Z})$.

So my question is,

are there any non-trivial representations $rho$ or cohomology classes $a$?

and secondarily,

would a non-trivial representation $rho$ give rise to a non-trivial $k$-invariant in the above situation?