School's out, omg.
First, if you haven't signed your kindergartner up for summer camp, do it. Decide what's right for you. There will probably be full-time and part-time options, sports camps, camps associated with schools, city or town camps and religious camps. Pick your poison, but seriously, do at least one, if not a few (if you can afford it...these things are really expensive.) We're thinking of doing one in the beginning and one at the end of vacation.
In the middle, plan a trip. We're going to my mom's for a couple weeks. It splits up the months so that they seem shorter on either end, and you can repeat what you did the first half in the second.
Do day trips or cheap staycations for holidays like Independence Day. Trying to plan your actual vacation for this week is like a death wish that costs a million dollars.
Check out all the free / cheap activities you can. In my city, they offer lots of activities every day. The libraries always have something going on, Tuesdays and Wednesdays certain movie theaters have $1 films in the mornings for kids. There are parks, and museums with free admission days. Don't forget playdates, too. Hopefully the more you host, the more your kids will be invited out (of course, it doesn't really work that way with twins, but we do what we can).
With all this, hopefully the weeks will fly by in a whir of fun and school will be there before you know it.