Canada as a whole is considered extremely friendly to gay travelers. Eastern Canada varies from place to place in the warmth of the welcome, but the cities are uniformly accepting.
Halifax doesn't have any one especially "gay" district, but GayHalifax (http://gay.hfxns.org) is a good online starting point to help you find out what's going on locally with activists. And Destination Halifax (www.destinationhalifax.com/rainbow) is the best online guide to the city's gay events that I've yet seen.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.