Much of continental Europe vacations in July and August--many people have an entire month off. I certainly wouldn't plan on doing much in the way of OAL standby on zeds. If you can be flexible and book LCCs to get out of Europe...I'd think in that direction. Lots of people get stuck, even in cities like AMS, where DL has some 15 flights and summer is a beast getting back to the States. I would not treat nonreving in July in europe lightly.