glaswegian, check out pickering nurseries, an online rose mail order based on Ontario. They offer many many choices for roses. Look for Explorer type roses. These roses were developed in Canada to withstand temperatures higher than zone 5. Avoid any hybrid tea roses which are not disease resistant.

I will second the vote for Pickering Roses. As for varieties, Double Delight is a wonderful HT and is disease resistant, but you should also think about the various rugosas. Check out the link provided for some varieties but many bloom all summer, they are as tough as nails, and in my opinion have the best rose fragrances around. My personal favourites are Blanc Double de Coubert and Roseraie de L'Hay.

Here is a link that might be useful: rugosas

The rosa rugusa is a great almost wild rose that is very hardy and blooms as long a you deadhead it. My favorite rose.

I love my Louis Odier: it is vigorous, very fragrant, and hardy. I planted one in a partial sun location and it is just as happy as can be. I also have a number of David Austin roses, but they are slow growers and I've lost a couple to harsh spring conditions.

I grow a number of DA's and they are hardy, beautiful and reliable, but they do get blackspot. Climbing Iceberg is a great rose. It is disease resistant, and at least in my garden is a no-fuss, constant bloomer.

I don't mean to be contrary, but I am not far from you and Double Delight (as well as other HTs) are BS magnets and would require a good deal of attention to keep them in good shape. I have SP'd all of mine...just not worth the work for the amount of blooms. Just my opinion.

I also own a couple of david austens. They are very pretty. And I also had owned a Louise Odier and so agree with jannabeen's testament to this plant.

Loblaws recently put out some David Austens and just for $14.99 a piece. Not bad.

Pickering is a great place to look around at all varieties you might be interested in.

I would stay away from Hybrid Teas because they aren't very disease resistant most of the time and are borderline hardy in Canadian winters. Some will make it, some don't and you have to protect them.

Look at David Austins for repeat bloom and great varieties/colours.

As far as Old Garden Roses (the heirlooms) ... Gallicas/Albas/Damasks are hardy but once bloomers. Noisettes/Chinas/Teas are not hardy this far North. Damask-Portlands are hardy and repeat bloom. Same with Hybrid Perpetuals. Rugosas are a good choice but can sucker pretty heavily (some people don't like that). The Explorer series is repeat blooming and bred for our cooler climate.

Its a wonderful website to peruse for hours though ... and then you can come back and get more specific opinions on more specific roses :)