Planning a 10-14 day trip with my 18 yr old niece. Soonest can start travel is June 6. Cannot travel June 19-June 22. And cannot travel after July 15. Any recommendations on best date options? I know both months are busy.
I would do early to avoid the heat
I would go earlier.
As stated, it will be a bit cooler.
Ditto the above. Except, if you're going to Normandy, early June will be crowded because of the June 6 D-Day anniversary. There, or in cooler Brittany, you might want late June/early July.
The earlier the better for less crowds, as well as heat.
Hôtel prices are fairly high this year. Use booking.com to see if early June is less expensive than late June or July.
French school holidays start around July 7, so it is better to travel beforehand.
Given the choice, June 6 - June 19 is slightly better from a weather and crowds standpoint.
Same as everyone has said - I would go for the earlier dates.