Because of their direct bandgaps and atomic-scale thickness, monolayer transition metal dichalcogenides have emerged as appealing materials for both classical and quantum optoelectronics. These 2D semiconducting materials, such as MoS2 and its related compounds, can support diverse non-trivial optical phenomena such as valley-selective exciton-polaritons and quantum emission from localized excitonic defects. Harnessing these interesting features for applications requires controlled tuning and manipulation to tailor the optical phenomena. Here, I will discuss examples of manipulating the optical and electronic environment of transition metal dichalcogenides that take advantage of the unique properties of these layered materials. Direct control over light-matter coupling is demonstrated through microcavity engineering in photonic devices. Quantum light sources are integrated into 2D optoelectronics for electrically pumped emission. I also show how coating with highly-customizable organic molecules leverages the exposed 2D surface of these materials for control of optical phenomena. The ability to influence optical response and defect emission using configurable organic molecules highlights the potential for optoelectronic engineering in low-dimensional heterostructures.