Hear Hear!
As always, the Dope is ever humbling in the scope of compiled knowledge it can display. I’ve learned more in this thread about the attractions around this city we’ve been calling home for the past 4 years than in any other guide or web page.
About scenic drives, we’ve done both the Vancouver-Calgary drive and the Banf-Jasper drive. I think you get a much greater bang for the buck driving that highway in the mountains between Banf & Jasper. Every turn offers a breathtaking view. It never stops. Although it can be done in only 4 hours, allow the whole day, as you will be stopping frequently to get out of the car, stare, and take pictures. And also to go on the Glacier in the Columbia Icefields about 2/3 of the way up.
Then stay in Jasper for a day or two, for great hiking (be sure to get a briefing from park rangers on bears & cougars and local/recent observations), mountain horse riding, and canoing, and then drive down again. It’s a new road coming the other way. Completely blew my mind when we did it. I suggest you do most of your non-free activities in Jasper, as prices in Banf can be astronomical by Canadian standards. (Still dirt cheap by Japanese standards, though 
)
Imho, the Vancouver drive was also nice, and the Okenagan was nice to visit, but it’s a lot more driving (12 hours total), with (although still great) fewer amazing sights.
Don’t buy any souvenirs in Banf, you can get the same things cheaper in Calgary, or even Canmore. If you’re into a bit of adrenaline, check out the “road-rocket”, a summer-time wheeled bobsled, at Canada Olympic Parc, site of the 86 winter games.
Let me know if you would like some restaurant recommendations for Calgary. Those I *do * know.
August is just about the best month to come, wheather wise. Bring a rain jacket, and a sweater / sweatshirt that can keep you warm if the mountain air chills down a bit. Something you would wear down to say 32F/0C is the most you are likely to need. We very rarely get more than a day or two of rain at a time. Also bring shorts & t-shirts & hat & sunscreen. Calgary is probably the most casually dressed larger city in Canada, compared to Montreal (*ha! order of magnitude!) * Ottawa or TO. Folks here won’t bat an eyelash if you walk into a seriously flossy restaurant in jeans & flannel shirt (personnal experience - boy that was strange for this Montreal native) . Downtown daytime business crowd still wears ties & jackets, but that’s about it. Khakis & golf shirts will be fine everywhere except maybe the wedding itself.
Calgary is not a shopping mecca, except perhaps for those living in the surrounding countryside. The malls are clones of just about any Canadian mall, although they service the local population well. Only possible exception is if you’re looking for “western” wear and comboy boots, which will be significantly cheaper than in the states. Ladies in your party would do better for a day with the girls to patronise a good spa, of which there are several in the area. I can give you some tips there if you want. If you’re in Canmore or near Banf, the spa at the Rimrock hotel is apparently quite amazing, according to my better half.
Do not hesitate to ask for help or directions. It astounds even other Canadians to see the extent to which Calgaryans will bend over backwards / go out of their way to help strangers. Big culture shock for us newcommers… Calgary is a very safe city, even by Canadian standards, with much lower crime rates than Montreal or Toronto. It’s safe to walk the streets even at night alone while tipsy.
Be patient on the roads. Most Calgarians are easygoing drivers. One thing to look out for is that many Calgary drivers are nervous about merging into oncoming traffic and can get stuck sitting at the end of the merger lane. Most fast drivers are likely new arrivals from the east, myself included. 
Well, that’s all I can think of. Hope you have a good time, and remember to book enough time to go visiting.
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