An LED-based luminaire, comprising: a lower reflective surface (112, 212, 312, 412, 512, 612a/b, 712); a rear reflective surface (116, 216, 316, 416, 516, 616, 716) extending upward from said lower reflective surface (112, 212, 312, 412, 512, 612a/b, 712); a blocking reflective surface (120, 220, 320, 420, 520, 620, 720) having a lower end and an upper end, said lower end more distal said rear reflective surface (116, 216, 316, 416, 516, 616, 716) than said upper end is to said rear reflective surface (116, 216, 316, 416, 516, 616, 716) and more proximal said lower reflective surface (112, 212, 312, 412, 512, 612a/b, 712) than said upper end is to said lower reflective surface (112, 212, 312, 412, 512, 612a/b, 712); a plurality of LEDs (140, 240, 340, 440, 540, 640a/b, 740) interposed between said lower reflective surface (112, 212, 312, 412, 512, 612a/b, 712) and said blocking reflective surface (120, 220, 320, 420, 520, 620, 720), said LEDs (140, 240, 340, 440, 540, 640a/b, 740) primarily directing a light output toward said blocking reflective surface (120, 220, 320, 420, 520, 620, 720) and including a first LED of a first color and a second LED of a second color distinct from said first color; a transmissive diffuser (30, 130, 230, 330, 430, 530, 630a/b, 730a/b) extending over said blocking reflective surface (120, 220, 320, 420, 520, 620, 720) and positioned between said rear reflective surface (116, 216, 316, 416, 516, 616, 716) and said lower reflective surface (112, 212, 312, 412, 512, 612a/b, 712); wherein at least some of said light output from said LEDs (140, 240, 340, 440, 540, 640a/b, 740) is reflected by said blocking reflective surface (120, 220, 320, 420, 520, 620, 720), said lower reflective surface (112, 212, 312, 412, 512, 612a/b, 712), then said rear reflective surface (116, 216, 316, 416, 516, 616, 716) prior to passing through said transmissive diffuser (30, 130, 230, 330, 430, 530, 630a/b, 730a/b); and wherein at least some of said light output is reflected by said rear reflective surface (116, 216, 316, 416, 516, 616, 716), without first reflecting off of said blocking reflective surface (120, 220, 320, 420, 520, 620, 720) and said lower reflective surface (112, 212, 312, 412, 512, 612a/b, 712), prior to passing through said transmissive diffuser (30, 130, 230, 330, 430, 530, 630a/b, 730a/b). a lower reflective surface (112, 212, 312, 412, 512, 612a/b, 712); a rear reflective surface (116, 216, 316, 416, 516, 616, 716) extending upward from said lower reflective surface (112, 212, 312, 412, 512, 612a/b, 712); a blocking reflective surface (120, 220, 320, 420, 520, 620, 720) having a lower end and an upper end, said lower end more distal said rear reflective surface (116, 216, 316, 416, 516, 616, 716) than said upper end is to said rear reflective surface (116, 216, 316, 416, 516, 616, 716) and more proximal said lower reflective surface (112, 212, 312, 412, 512, 612a/b, 712) than said upper end is to said lower reflective surface (112, 212, 312, 412, 512, 612a/b, 712); a plurality of LEDs (140, 240, 340, 440, 540, 640a/b, 740) interposed between said lower reflective surface (112, 212, 312, 412, 512, 612a/b, 712) and said blocking reflective surface (120, 220, 320, 420, 520, 620, 720), said LEDs (140, 240, 340, 440, 540, 640a/b, 740) primarily directing a light output toward said blocking reflective surface (120, 220, 320, 420, 520, 620, 720) and including a first LED of a first color and a second LED of a second color distinct from said first color; a transmissive diffuser (30, 130, 230, 330, 430, 530, 630a/b, 730a/b) extending over said blocking reflective surface (120, 220, 320, 420, 520, 620, 720) and positioned between said rear reflective surface (116, 216, 316, 416, 516, 616, 716) and said lower reflective surface (112, 212, 312, 412, 512, 612a/b, 712); wherein at least some of said light output from said LEDs (140, 240, 340, 440, 540, 640a/b, 740) is reflected by said blocking reflective surface (120, 220, 320, 420, 520, 620, 720), said lower reflective surface (112, 212, 312, 412, 512, 612a/b, 712), then said rear reflective surface (116, 216, 316, 416, 516, 616, 716) prior to passing through said transmissive diffuser (30, 130, 230, 330, 430, 530, 630a/b, 730a/b); and wherein at least some of said light output is reflected by said rear reflective surface (116, 216, 316, 416, 516, 616, 716), without first reflecting off of said blocking reflective surface (120, 220, 320, 420, 520, 620, 720) and said lower reflective surface (112, 212, 312, 412, 512, 612a/b, 712), prior to passing through said transmissive diffuser (30, 130, 230, 330, 430, 530, 630a/b, 730a/b).