Solid state lamps and bulbs comprising different combinations and arrangements of a light source, one or more wavelength conversion materials, regions or layers which are positioned separately or remotely with respect to the light source, and a separate diffuser. These are arranged on a heat sink in a manner that allows for the fabrication of lamps and bulbs that are efficient, reliable and cost effective and can provide an essentially omnidirectional emission pattern, even with a light source comprised of a co-planar arrangement of LEDs. Additionally, this arrangement allows aesthetic masking or concealment of the appearance of the conversion regions or layers when the lamp is not illuminated. Various embodiments of the invention may be used to address many of the difficulties associated with utilizing efficient solid state light sources such as LEDs in the fabrication of lamps or bulbs suitable for direct replacement of traditional incandescent bulbs. Embodiments of the invention can be arranged to fit recognized standard size profiles such as those ascribed to commonly used lamps such as incandescent light bulbs, while still providing emission patterns that comply with ENERGY STAR® standards.