I am doing a lot of analysis of airfares, but I know that shouldn't be my only influence.
As tourists, would we see a big difference in price, crowds, etc in August over July? Our tentative plans include some combination of a few days in London, a few days in Paris, 5-7 days in Provence, 4-5 day Southern Germany, or 4-5 days in Ireland, totalling about 17 or 18 days once we finalize our priorities. We will leave out at least one of those locations but not sure which, yet.
I keep reading that "Paris empties" in August, and it seems it empties into Provence--so maybe that area will be more inflated or overbooked? Will August vs July make much difference in Germany, Ireland and London? (I have never travelled in high season, but with teens, it's that or not at all.)
Our dates are firmly in high season, as my son is in school until June 28--10th grade, so no skipping out early--and they return to school the first week of Sept. Airfares in August are much better for our purposes than the July fares.
We will do an open jaw, and our gateway airports are DUB, LON, PAR, or Frankfurt. (Again, which airports exactly is still tentative, and date matters...prices in July are quite high to France and Germany, whereas London and Dublin are ok in both months.) We are flying from a small market (Halifax Nova Scotia) so we don't have a lot of choice on where we touch down in Europe. It's our first trip with the children, and they are interested in London and Paris for sure. Dh and I travelled in Ireland, England and Germany pre-kids. France is new to all of us.