1st 2 choices, I would put both down, as CP is a huge for requests.
I would vote for Congress Park for views of DTD. (and prox to main pool.) or Padd for prox to new pool.
Grand stand is near splash park, but based on kids ages, I would put CP and Pad way over for this one.
I would avoid Springs and Caras all together. Springs is center to the main bus route. Caras is for sure the most secluded if that is a goal, but also is the furthest away from all the pools, and everything. I hate this section. A solid walk to pool, DTD, Artist Pal, everything.