Here's are somethings I do to make things better.

Do Nature things (read The kids summer handbook)
Get lots of outside time
Get lots of exercise
Make a point of giving a big smile and tell you love him when you see him in the morning and after school and before bed.
Try to just play with each child at least 15 minutes every day. My kids seem to really want this. It doesn't seem to count that I watched them play soccer for a hour.
Hope it's helpful.