After doing Route 66 in 2012 we would like to do a trip from New York down to Miami taking 3 weeks to do it have no idea where to start or who to fly with we are in the uk any tips looking at going sept 2016 know it's a long way off but I think it's gonna take one planning

Is US Rt. 1 the road you want to travel?
http://www.historicrouteone.com/history.php
The route starts in Maine and ends in Miami.
You could start in Quebec or in Boston or maybe Portland Maine.
The route was at one time called "Tobacco Road".

You need to understand that this is a local road through a VERY highly populated area - going through many town centers and in many places with traffic lights every couple of blocks. Also - although near the coast you aren't within sight of the sea. I think you will find this is an incredibly slow route through huge masses of suburbia - and would take forever while you are wandering through a huge series of strip malls.

3 weeks isn't enough time to drive the east coast...especially via Route 1. Since you are planning September, I would focus on the New England area.

These will not be detailed directions but a strategy.

If you don't want to do the Fall in New England thing, you should fly to Newark (assuming you have already done NYC) and drive the Garden state Parkway to Cape May. Take the ferry to Lewes, Delaware.

From there, follow US 9, 113, and 13 to the Chesapeake Bay Bridge-Tunnel. Once across, find US 17, which will take you all the way to Yulee, Florida. From there, take Fl A1A from Fernandina Beach to Cape Canaveral, and US 1 to Miami.

If you look at the map, you will see that you pass near a great many desirable places and parallel enough of Interstate 95 that you can always bail out if you need to make up time by driving the US equivalent of the M1. Avoid the temptation to drive any route that takes you near Washington on Interstate 495. It is our M25.

It isn't a lot of time for the trip, so you might want to do it over three years: Montreal to NY through New England, Newark to Jacksonville as described above, and Florida.

You could move away from the coast too...fly into Dulles, drive thru the mountains of Virginia and north Carolina. Spend time in Asheville. Head home from Atlanta.

We've done the route Ackislander planned on a couple of trips and if you enjoyed 66, it will give you a much more relaxed trip than 95 once you get to the Cape May ferry. There are several places to visit along the way south.

Chincoteague Island, Williamsburgh, Charleston, Savannah and St. Augustine are all either on or just a short distance off the route.

Heading west through PA and then down Blue Ridge pky/Skyline Drive to the Smokies then through the south to FL would be a different but also interesting trip too.

I would hop on Highway 17 in South Carolina and stay on it until you are forced to drive I95 to North Florida then take US 1/AIA all the way down the coast of Florida. You'll dead end in South Beach but you can drive east to the turnpike and US 1 it to Key West.

Georgia and North Carolina have barrier islands so driving along the coast really isn't too much of an option.