  We study the interplay of intrinsic-electronic and environmental factors on
long-range charge transport across molecular chains with up to $N\sim 80$
monomers. We describe the molecular electronic structure of the chain with a
tight-binding Hamiltonian. Thermal effects in the form of electron decoherence
and inelastic scatterings are incorporated with the Landauer-B\"uttiker probe
method. In short chains of up to 10 units we observe the crossover between
coherent (tunneling, ballistic) motion and thermally-assisted conduction, with
thermal effects enhancing the current beyond the quantum coherent limit. We
further show that unconventional (non monotonic with size) transport behavior
emerges when monomer-to-monomer electronic coupling is made large. In long
chains, we identify a different behavior, with thermal effects suppressing the
conductance below the coherent-ballistic limit. With the goal to identify a
minimal model for molecular chains displaying unconventional and effective
long-range transport, we simulate a modular polymer with alternating regions of
high and low rigidity. Simulations show that, surprisingly, while charge
correlations are significantly affected by structuring environmental
conditions, reflecting charge delocalization, the electrical resistance
displays an averaging effect, and it is not sensitive to this patterning. We
conclude by arguing that efficient long-range charge transport requires
engineering both internal electronic parameters and environmental conditions.
