Patio - cement foundation vs gravel/traffic bond...
If you are just putting in a patio and considering interlocking concrete pavers (up to 10" maximum horizontal dimension), you probably need about 6" of compacted road base over the caly with the top sloped for drainage and and uniform 1" thick setting bed of clean, uncompacted concrete sand. Set the pavers tightly, sprinkle fine sand an compact with a plate vibrator to even the surface and create the structural interlock - common method used internationally.
For concrete a compacted similar base id adequate and make sure you have control joints to control/hide cracks, depending on the size.
For Bluestone, I cannot offer much because of the limited exposure for a small use variable product by comparison.
You have several producers of interlocking concrete pavers (60mm, 80mm thicknesses) with different shapes in your area and they are also available in the big boxes (at least the 60mm) in many different shapes for use in different patterns. Specialized suppliers will have more options.