trip from North Florida to Niagara Falls

Rule of thumb is generally 50 mph when you factor in fuel stops, bathroom breaks, etc. You didn't specify where in North Florida but using Jacksonville as a starting point it's almost 1100 miles. I'd plan on 3 days travel each way for comfortable travel and allowing for unexpected delays such as traffic. That will leave you with about 9 days of touring. Depending on how long you want to stay in NY, you might want to cut out a stop or 2 on the way. What do you plan on seeing in Hershey, VA, etc? That may help out with suggestions. We weren't impressed with Hershey Park-half the rides were out of service. That was a number of years ago. I'd also suggest making reservations now. Once everyone starts to break free these places are going to book fast. Even if all restrictions aren't lifted, which they aren't likely to be, those of us who have been vaccinated will be much more likely to venture out.