Hmmmm..... I'd love to give you some more suggestions ILUVDXL, but I'm not certain as to exactly what you're looking for.
Halifax is the largest city in the province... but it is hardly comparable to Boston! It has a nice waterfront area and downtown district with shopping, restaurants etc.. The "night life" is concentrated in mostly 1 area, so it is possible to avoid if you wish. (Bar district) Halifax offers many larger hotels as well as a lovely variety of Bed & Breakfasts/Inns.
If you would prefer to avoid Halifax all together there are MANY smaller towns to consider. There are some resorts that aren't TOO far from the ferry, and there are MANY, MANY B&B's to choose from.
Everyone is different... (not certain if your party is just 2, or +kids?)... My personal preference would be to spend the time visiting the smaller, picturesque villages of NS, choosing smaller Inns for accomodations, and spending my days exploring the local shops, restaurants, etc..
Let me know what "kind" of vacation you're looking for, and I can narrow down some choices for you.