The continued evolution of quantum technologies in diamond requires heterogenous material platforms for sophisticated functionalities, device integration and packaging, and improved qubit performance. At UChicago and Argonne National Laboratory, we are creating pristine single-crystal diamond membranes that host coherent color center qubits and integrating them with a wide range of materials including fused silica, sapphire, thermal oxide, lithium niobate, tantalum, silicon and YIG. The membrane uniformity and robustness to fabrication enables several varieties of integrated nanophotonic cavities – critical elements in quantum photonics - with record quality factors. Furthermore, we show that our ultra-thin diamond membranes are compatible with total internal reflection fluorescence (TIRF) microscopy, which enables interfacing coherent diamond quantum sensors with living cells while rejecting unwanted background luminescence. Remarkably, we demonstrate that membrane integration can improve the spin coherence and microwave addressability of tin vacancy qubits while maintaining exceptional optical coherence, allowing us to create an operational spin-photon interface at 4 Kelvin. In total, the combination of qubit performance, high-performance device fabrication, and flexible materials integration will enable a broad range of quantum photonic, acoustic, and sensing science and technologies. We will also demonstrate that color centers can function as optical antennas that can efficiently concentrate optical energy in solids, with up to million-fold local intensity enhancement under resonant excitation, and discuss potential applications in spectroscopy, sensing, and quantum science.