Easter is the last Sunday in March so that, despite the relatively mild and dry winter, is still winter in the mountains and I'd suggest being prepared accordingly unless forecasts for the mountains at the time promises something drastically different. Keep in mind that it is the beginning of mud season when trips off the beaten path (highways), which are normally the best places, can be troublesome, if not impassable.
You appear to have a variety of Northeast mountain experience so a bit more detail about your interests might help come up with suitable destinations. Is it a group? Are you interested in wildlife, scenic ponds or waterfalls or just getting out and stretching your legs? Of your 4 days out would you seek a base camp with day hikes from there, three different sites that eventually lead back to the car, or some combination of that?
We are aware that everything in the Northeast is two hours from Sherbrook but what about Ottawa, how far are you willing to travel realistically? Strikes me that there are better seasons to do this if you, say, need to drive several hours to get to Maine or very far south in NH. As for AMC trips, it can be a good place to meet people and develop more experience but check it out even if that is not your objective. If some description catches your eye you might do it independently.
My favorite places in Maine are off long gravel roads so I'd avoid that in mud season. The WMNF has some cabins that rent inexpensively and might be good base camps; Black Mountain, Doublehead Mountain and one right on the Kanc which has easy access to the many trails off the Kanc. Sawyer Pond has a leanto and tentsites and is another possible base camp especially accessible to Carrigain and Vose Spur as well as other hikes and bushwhacks.
Enjoy whatever you decide on.