I'm not familiar enough with the areas to really give you details on most of your questions, but I've taken separate trips to ND and SD in the last few years, so I do have a few thoughts that might be helpful.

I really can't imagine taking a bus around ND and SD unless it's an organized tour specifically going to tourist destinations. There is a lot of relatively "empty" countryside, and some long distances between the places you're likely to want to visit.

On the other hand, I think driving in the area would be a lot easier than driving in New England. Certainly no "big city" driving (assuming you get a car outside Chicago)

In ND, my absolutley favorite place is Teddy Roosevelt National Park. Beautiful scenery and wildlife, and a wonderful drive around the Park so you don't have to walk too much. There are some nice hikes, but you can see a lot without much walking. My other favorite spot was Grand Forks, just a cute little city and I liked the college, but it's a bit of a drive from the western part of the state, and unless you really had a lot of time, I'd probably focus more on SD and Teddy Roosevelt.

Lots to see in the Black Hills area of SD. The road to the Badlands National Park is flat and open - sholdn't be a problem. The only problem I see driving in SD is that some of the areas in the Black Hills have windy narrow roads in the hills. If you're not comfortable driving in the US, that could be a problem, but it's more a matter of high, narrow roads, not traffic. There are ways to see the sites without going on those roads, but it might take more planning.

Anytime people visit SD, I put in a recommendation for Custer State Park in SD. Great wildlife drive that also wouldn't involve much walking.

I'm not a big Lewis and Clark fan, but there is a lot of information about historical sites related to their journeys that you might find interesting and helpful.

Weather in May could be iffy. I'd recommend June if you could delay, but check the weather sites for average temperature ranges to give you more detail.

some of the locations you mentioned aren't big on B&B, particularly in the state or national parks. I'd recommend reservations at the state or national park lodges, but I tend to be more comfortable with reservations.

Hope that helps at least a little.

Travelkitty
Thanks for all your help.
As our flights are booked (we got a good deal booking early) it has to be May but probably not till mid-May.
We have noted all your suggestions but are still thinking of using the bus rather than a hire car! Looking at the Greyhound schedules it does seem possible.Plenty of time to plan anyway.
Thanks again

Even if you can use Greyhound to get to a location, I don't see how you'll really be able to see the sites in SD and ND without a rental car. You may be able to hire a tour guide for the day, but those locations really aren't big on public transit (like Chicago or other big cities).

However, those are some of my favorite spots in the US. Very different from the Northeast and off the beaten path for most international visitors. If you can work out the transportation, I think you'll really enjoy the trip.

FYI, here is the site for Custer State Parks in South Dakota that I mentioned. I stayed at the Sylvan Lake Lodge and enjoyed it - sort of old and basic, but a great location.

http://custerresorts.rtrk.com/?scid=634949

We just came back from this area and drove from Madison WI to Yellowstone and back.

One thing I can say about the driving in ND & SD & WY & Montanta is there is hardly any traffic. It was really easy driving. However, if you aren't used to our "side of the cars", driving in the badlands and Custer State park would be tricky because of all the sharp turns and no guardrails.

I don't think you will find a bus that will take you to where you want to go after you leave the train. You may have to rent a car..get Rapids city or wherever ...and possibly they would have a local tour or guide that could drive you to see the sites.

Teddy Roosevelt Park was beautiful and so is Custer park (Twisty roads).

May could sitll bring snow.

Hope you have a nice trip.

If taking the train from Chicago, I would highly recommend traveling into Fargo. That's your best place to obtain a rental car, which you will definitely need, as public transportation is almost nill in this rural state. Driving from Fargo to Jamestown to Bismarck to Dickinson is about 100 miles between each city (about 1 1/2 hrs per segment) or about 5 1/2 hrs from one end of the state to the other. It's all 4-lane interstate road, with very flat or gently rolling countryside - easy, comfortable, light traffic!! The weather in mid-May could be pretty, but it could also be cool,cloudy and rainy. I agree that bus connections are iffy, and you would still need a car when you reach these cities, as Fargo is the only city with public transportation within it's city limits. This truly is a very rural state!!!
As many graduations take place in May, I would suggest making room reservations to be safe. The Holiday Inn Express chain can be found in all four cities, and I would guess if you chose Bed & Breakfasts, they would be very hospitable at taking care of your needs. Try the website DiscoverND.com for information on this state.

What is your country of origin?
Why the Dakotas?

Traffic is very light. Driving will be much easier than in New England.

Thanks for your replies.
Our country of origin is Scotland.
Why the Dakotas? No real reason apart from the fact that it is somewhere I have always wanted to go!We have visited a lot of the US and prefer the quieter less touristy areas.We are flying into and out of Toronto, want to visit Chicago and Nebraska!Do you think we should try somewhere else instead of the Dakotas? We are away for 4 weeks.
We are open to any suggestions as the holiday is still in the planning stage!

Driving a car is much safer then taking a Greyhound bus.

No, just wondering. There seems to be a lot of visitors to that area from "across the pond" whereas most Americans have never been there and don't think of the area for vacations/holidays.

I'm guessing there's a very effective PR campaign going on. I'd just like to see the adverts.

Okay. You asked.
If you are flying in and out of Toronto, I'd change the departure to out of Calgary.

Then, instead of a loop returning back to Toronto, I'd do a big one-way trip.

Driving out there is easy. If I can drive in Scotland, you can drive in the great American west.

Get out of the metro area(s) and rent a car. Then, do the Dakotas if you want, but continue on to Yellowstone National Park, then up to Glacier NP and then the gorgeous Canadian Rockies too. Some of the prettiest countryside I've ever seen.

With 4 weeks, you have plenty of time.

Thanks Starrs.That would have been a good trip.Unfortunately our flights are booked and paid for (we got a very good deal!)Also as we have friends in Alberta and BC we have visited Glacier national Park and the Canadian Rockies quite a few times!Maybe we should think of going south from Chicago instead of west if the weather in May might be iffy!Nebraska would have to be fitted in on the way there or back!We always book flights first then decide where to go!