So much of the great time I had in Montreal can be attributed to the Hotel St-Denis. Honestly, though, it's not that the place is palatial or awe-inspiring or in any real way a good time in and of itself.
Now, don't get me wrong: the hotel is great.
It's clean, accommodating, wonderfully understated, and serviced by a friendly staff. The thing about the Hotel St-Denis, though, (and this is particularly important for international travelers) is its location.
The location is tops.
The Hotel St-Denis is surrounded by bars, restaurants, and enough bus/metro stops to make vacationing easy for even the densest of people (i.e. me: The Meandering Traveler). Staying here makes visiting Montreal as easy as walking in any given direction for a few minutes. Further, other curiosities (like Montreal's many cathedrals, its museum, and Old Montreal) are close enough that you don't really need a cab (bear in mind that "close enough" just means that travel by car isn't REALLY necessary, but if you're not ready to walk upwards of five-to-ten miles round-trip, ignore my last observation).
Lastly (and of greatest delight to me), the neighborhood is NOT family-friendly, so if you're traveling with a gaggle of children and a nagging spouse, your best bet is Old Montreal. If, however, you're a bit younger (in body and/or mind) and fancy yourself a bit more progressive in ideals, don't even consider staying elsewhere. Drop the Hotel St-Denis a line and inquire as to how soon they'd be willing to accept your money.