Hi my wife and I are planning to come to America in June 2017 for a road trip from NY to OR, we are going to have about 21 days.
We are from New Zealand and have never been stateside before so we are doing some research on what to expect. We enjoy the smaller cities and towns being from a small rural town ourselves, but we want to see a few of the landmarks that are well known worldwide.
We have drafted a itinerary some places are just a stab in the dark on a map between destinations so I thought I'd post our plan and if anyone wanted to offer any advice that would be great.

Day 1
Arrive in New York City

Day 2
Explore New York City

Day 3
New York to Utica - this is the first stab in the dark

Day 4
Utica to Niagara Falls

Day 5
Niagara Falls to Lorain OH

Day 6
Lorain to Chicago

Day 7
Explore Chicago

Day 8
Chicago to Cedar Rapids

Day 9
Cedar Rapids to Sioux city

Day 10
Sioux City to Oacoma

Day 11
Oacoma to Rapid city

Day 12
Rapid city to Gillette via Mt Rushmore

Day 13
Gillette to Cody

Day 14
Cody to Yellowstone national park

Day 15
Explore Yellowstone

Day 16
Yellowstone to Missoula

Day 17
Missoula to Coeur d'alene

Day 18
Coeur d'alene to Seattle

Day 19
Explore Seattle

Day 20
Seattle to Portland

Day 21
Fly home


Thanks for your help,
Ben