Hiking near Halifax (Nova Scotia, Canada); half a day of free time

This summer I'm going to visit Halifax for a conference. After the conference ends (~2PM), I'll have the rest of the day for myself, then will have to clear out of the hotel next morning (~10AM) and get on a plane that leaves at ~10PM.

I would like to visit one of those nice hiking trails you can read about on websites like Halifax Trails or even at the official website.

Is Long Lake Provincial Park my best option, with it being accessible by public transportation and having a wide spectrum of trail difficulty? What should I keep in mind? Do I have any other options?

My priorities are somewhat conflicting: I want a middle-difficulty trail for it to be interesting but I'm also time-constrained and I'll have nowhere to store my luggage (an 80L backpack, probably) on the last day. (It's probably not a good idea to go hiking on the flight day, anyway.)