How about a band of the stone used in the fireplace and columns?

I think if you try to match as good as you can with same pattern and color, given that you have a nice straight line that correlates with the pavilion, it will be fine. I also think you could separate it with a uniform band of different material -- like concrete colored brick/pavers -- and it would also be fine. Of course, get samples and mock it up first, in order to get the exact details and color right. I also think it's possible to transform to a completely different paving, but it should not visually compete with the original paving. It should be compatible ... like "white" space. You might explore ground/polished/acid-stained concrete as one option. It could look like a large, single slab of "stone" in the same color family as your existing paving. I would not do anything with much texture to it.

I agree that trying to match the existing concrete and color would bug you forever if it didn't come out perfect (it would me). Because the pavilion is a distinct space, you can change the texture and pattern. However, so the contrast is compatible, I would go with Belgard LaFitt Rustic Slab modular pavers that would mimic the existing pattern, yet look different enough so that it is obvious you are not trying to match.