The coaches I spoke with have a hard time with the Fireworks and the Sparkler due to the space and distance between fields. They felt that too much time was needed to drive between facilities and as one coach said, "If it doesn't happen at the main facility, I won't see it". Boulder is preferred simply because it is more compact and less road time is spent going from place to place. So I've been told.
Heard the same from more than one coach. DD played once in Fireworks, twice in Sparkler, and once in Boulder. No question that Boulder had the most coaches in attendance. Not uncommon to be on the remote Sparkler fields with zero coaches present. Also heard from a couple of coaches that they don't generally go to Sparkler pool games. Prefer to wait until bracket play starts and then focus only on the top two brackets - perception (reality?) that the lower bracketed teams just don't have enough players with the desired talent level.