If you have lodging elsewhere, consider booking a "throwaway" room at one of the deluxe resorts for the sole purpose of getting express pass. Depending on how many in your party and the rate you can get, the room at the resort can be cheaper than purchasing unlimited express pass for each person in your party. Plus it gives you a place to relax for a bit if you're doing full park days.
Another option is to book one night at one of the deluxe resorts (to stay at or just as a throwaway room), which would give you unlimited express pass all day on your check-in day AND your check-out day. Two full days of unlimited express pass for the cost of one night at a deluxe resort. You could focus on the headliners during your express pass days, and do everything else on your days without it.
I personally never go without express pass, no matter the time of year. I agree that June is a busy time which makes it even more worthwhile.