  The normal and superconducting state of YBa_{2}Cu_{3}O_{6+\delta} and
Bi_{2}Sr_{2}CaCu_{2}O_{8+\delta} are investigated by using the mono- and
bilayer Hubbard model within the fluctuation exchange approximation and a
proper description of the Fermi surface topology. The inter- and intra-layer
interactions, the renormalization of the bilayer splitting and the formation of
shadow bands are investigated in detail. Although the shadow states are not
visible in the monolayer, we find that the additional correlations in bilayers
boost the shadow state intensity and will lead to their observability. In the
superconducting state we find a $d_{x^2-y^2}$ symmetry of the order parameter
and demonstrate the importance of inter-plane Copper pairing.
