Family backpacking, 2-3 nights, from Heart Lake campground?

Hi all! My family (2 adults, 2 teenagers, 1 dog) will be staying at Heart Lake between Aug 21 & 26 (2017). We would love to do an actual backpacking trip during that time, meaning 2 (maybe 3) nights actually tent-camping on the trail. Where can we go? We've never hiked in this region. We are in decent shape (especially the dog), but the kids have never backpacked before. I think we could easily walk 6-ish hours per day (that could be 10-12 miles depending on the terrain, I guess). Can anybody suggest a route for us, starting at Heart Lake campground? THANK YOU!!