3 more days of school~Oh My!!

The kids only have a few more days of school. This is my first year that I am not working. The kids have always gone to daycare full time all summer long. I have never had three kids on my own for so much time. I am nervous. I am worried I won't be able to keep them entertained but I am also excited for them to enjoy their summer fort he first time. I must admit that I am totally clueless to what I can do with all of them everyday. Brendan definitely makes things more difficult like going to the beach, going grocery shopping, and just really every day activities. It is really hard for me with all three.
I am over the fact that they won't behave because for the most part all three are excellent children. I think it is the logistics of getting all of them somewhere without totally exhausting myself. Parks are pretty much out because I can't leave Brendan walking by himself or he will most likely fall. He likes to try dangerous things in his walker. Makayla is 3 and is into climbing everything all on her own and she is NOT graceful to say the least. There is no way I can watch both of them at the same time. I could go up to the school playground and let Bren walk around the parking lot while his sister's play but how fun is that for him??? Not to mention putting Bren down slides multiple slides can wear you out in minutes.

I can't picture myself taking them to the aquarium or zoo all on my own but maybe I can do it. Maybe once I start doing it I will realize it isn't so bad and I CAN do it! I guess we will find out very soon. Brendan can't physically keep up with his sister's so I do not know what he will do all day long at the house. He can walk around the yard but how much fun will that be. He can swim in the little blow up pools we have. We have the water slide but I doubt I can lift him too many times to go down the big slide all by myself.
Anyone have good ideas for the summer? I need to start thinking and planning!