I would say do the parks closer to the evening. (Less sun) Let all the early birds get in and out. Parks are open later in the summer so take your time. Just play it by ear this is going to be fun for them and whatever you get in make it the best. I would suggest buying clip on fans for the strollers. I think they have then at local drug stores. I used them with my kids and it helped a lot. Especially when they are sleeping (nice and cool) Also since it gets really humid. I would freeze some apple juice (or whatever they like) and have it in a lunch type bag to throw under the strollers also snacks they like. If a meltdown occurs just remember they are small and it can be very over whelming to them to be in the strollers with tons of people coming at them. Oh yeah and if you can I would get the strollers that recline. Poor kids I see them all the time with their head slumped over looks uncomfortable. For the adults they have this really cool towel thing at Bass pro. That you freeze and it stays cool a long time. I would grab a few of them for whomever in the group gets really hot. Hmm I think I’m going to get a few for us too. For July. All and all just remember there is plenty to do with them just take your time and enjoy seeing it through their eyes.