Of more general interest is the fact that the big Greek exhibit (that we just missed in Montreal) will also be at the Canadian Museum of History through mid Oct. I think we can manage to make it there in time. I believe the exhibit moves on to the Field Museum in Chicago and then to a DC museum in 2016, but I'd rather try to catch this in Ottawa in the fall. I'll try to make sure it isn't so last minute this time around.
I wouldn't see there are any must see exhibits at the National Gallery (the Alex Colville is a good exhibit but I saw it several times at the AGO). I will try to make it to the Chagall Daphnis and Chloe exhibit, but that would mean we have to go by the first two weekends in September. That might not work out.
In any case, I mostly want to focus on the Pompeii exhibit at the ROM, which we saw two weeks ago. This exhibit runs through the first week of January, so there is plenty of time to go see it. My daughter basically did not want to go, as she was somewhat worried about seeing skeletons or the "insides" of bodies. Nonetheless, I convinced her that it wouldn't be too bad. I wasn't sure whether there would be the body casts or not (due to the somewhat mature content), but there are in fact 5 groups of casts, and about 10 bodies in total.
The focus of the exhibit is in fact on everyday life in Pompeii, as reconstructed from the very detailed artifacts left behind. They had quite impressive mosaics and paintings in the villas. (The second one below is thought to represent the 3 Graces: Aglaia (Beauty), Euphrosyne (Mirth), and Thalia (Abundance).)
There is even a small marketplace for kids to pretend that they are buying and selling goods. That was probably their favorite part of the exhibit, though there was also another interactive area where you could put together tiles in a sort of mosaic.
Towards the end of the exhibit they focused more on the devastation, including the eerie beauty of these melted bottles (even my daughter liked these).
And of course some representative casts. I suppose it would simply be too disappointing for most people seeing an exhibit about Pompeii not to feel that human connection.
It's definitely an interesting exhibit for anyone interested in ancient Italy, though I wouldn't recommend it for anyone with very small and/or sensitive children.