Best Route From Florida To Maine Avoiding All Major Metro Areas

What is the best route for road trip to cover maximum must visit places in USA from July to October 2016 (approximately 50 days)?

This is a very hard question to answer because everyone has a different idea of what  a "must visit" place is and many of the "must visit" places are far from each other and in distant locales. I would start by making a list of the places I "must visit".  For example, the Grand Canyon, Yellowstone National Park, Mt Rushmore, the Smithsonian Institution, Key West Florida, New York City, Niagra Falls, and of course, the jewel on the list, Boston, Massachusetts, my fair city and the best place on the planet. While you are there you can go to Cape Cod. Then I would get a big road atlas of the US and find the best routes. The United States is very large and 50 days is not a lot of time to see that list I provided and what's going to happen is that along the way you're going to be diverted by things you never thought of but really want to see, like the World's Biggest Ball of Twine. There are other things you will want to do your research on as well. For example, many people want to go see the St Louis Arch but unfortunately, St Louis is a very dangerous place and if you get lost aound there you're in serious, serious trouble. If you aren't prepared for what you're getting into you could get into much more than you bargained for. Having been there a few times, I would avoid St Louis. The highways in the US are well laid out. Because of the Interstate Highway System one always knows where one is. The East-West highways start at Route 10 down south and end at Route 90 near the Canadian Border. You can always generally figure out where you are just by the route numbers, 10, 20, 30, 40 and so on. The odd numberer highways go North - South. Route 95, for example, goes from Maine to Florida. The highways are good for fast movement but that also prevent you from seeing things along the way -- you're going too fast. But if you have a list and a map you can plan the best routes just drive from Point A to Point B. Using Google Maps or Mapquest you can determine the drive time between destinations and plan your overall travel time budget. If there is someplace you MUST, such as Butte,  Montana then you need to plan for the time on the road as well as the time you will take to get there. It takes about a week to drive across the country even if you aren't stopping to see anything along the way so you're going to need a plan. Start with the list of things you MUST see, then plan the route on a map and leave some wiggle room along the way. It will be the trip of a lifetime.

What are the best U.S. road trips for an active senior adult couple?

My thoughts:Interstate 40 coast to coast - A lot of things to do and see (the Grand Canyon, many areas of New Mexico, the Ouachita Mountains of Eastern Oklahoma/Western Arkansas, Memphis, the Smoky Mountains of Tennessee, the Biltmore House in North Carolina, etc.) and all of this can be done with only being 5-6 hours at MOST from a major city if you want to sleep in a nice motel/hotel or have any medical issues or concerns.I-10 Coast to coast - Again a number of things to do and (Los Angeles Metro, many areas of Arizona, Big Bend National Park in Texas, the Texas Hill Country, San Antonio, the Houston area, New Orleans, the Florida Panhandle, etc.) As with I-40 there are only a few spots where you are a significant distance from a major city in case you want to (or need to) stop in one.I-95 Corridor (Maine to Florida) Basically the busiest route in the United States. Anything within 100 miles of the Atlantic Ocean is near to this route, with Boston, NYC, Philadelphia Washington D.C., the Outer Banks, Hilton Head/Myrtle Beach and the Florida coast being among the highlights. The only caveat is that it is extremely busy and there are often bottlenecks around New York, Philly, Baltimore and D.C.I-70 - The most scenic of the interstate routes especially in Colorado and Eastern Utah. Unfortunately it is also one that is most vulnerable to problems with the weather. From snow in the mountains to rain and tornadoes on the Great Plains, I-70 is definitely a route that you want to check your weather ahead of time.I left off I-35 (dull), I-75 (really only the Southern KY-TN-North GA area is scenic), I-90 (dull until you get to Montana), I-94 (Interesting in Chicago and around Milwaukee/Madison; dull the rest of the route), I-5 (surprisingly dull for most of its run) , I-80 (Dull and long stretches without services) and I-15 (Dull until you get into Utah and then onward to Canada) There are, of course, exciting US highways (US-19 through the Appalachians, US-1 along the Atlantic Coast to the Florida Keys, US 89 through Monument Valley and across the Grand Canyon are examples) . I just concentrated on interstates as they are faster and present more options in my opinion.