I would like to get a list of sights along the route from Chicago to Niagara falls via Cleveland.
How can one proceed when trying to obtain a list of sights in unknown area for further selection?
Go geocaching. Geocaching is an online game where locals hide something - a cache - typically a box or small container, where the objective is for you to find it with the help of a gps device. Usually the geocaches are hidden at nice locations. So to locate some good sights just explore the various geocaches on their website hidden on route to your destination and you will have a nice collection of sights. Caveat: It is a sight according to local preference, so not necessarily a touristic sight.
Back in the day, you bought guidebooks. I still use these for some trips because it's fun to curl up with them when you're still trying to settle big questions like how long the trip will be or what cities to include.
For lower key destinations, or to save money and shelf space, the internet, of course, is your friend. Countries, provinces, states and cities all have tourism sites. Search for "[placename] tourism", skip all the sponsored links, and look for domains that suggest some sort of official status. For example prefer http://niagarafallstourism.com/ which includes this "seal"
to random hotel sites, trip advisor etc. If you really value paper, many of these places will send you their brochure if you call and ask.
Once you've had a pass at what the people who are paid to encourage your visit have to say, then head to a hotel aggregator or travel review site (they can be hard to tell apart.) TripAdvisor, hotels.com, booking.com, they're not hard to find, they generally all buy ads on each other so you can wander around from link to link. Read the hotel reviews, but not to find out about the hotels. Reviews often include details on attractions the person visited, restaurants they ate at, and other things that are irrelevant to the hotel. Say you read "very convenient if you're planning to visit X" then you know X is a thing people visit there. Many of these sites also include attractions lists, with prices, pictures, and reviews.
Make a giant list (I like to put things in the order we will do them), add comments, and search for attractions once you know their names, so you can see if they are something you want to visit or not. As well as just typing the name of the attraction into a search engine, try sites like Flickr and Instagram to see pictures people took at the places, for example. Delete the things that are too expensive, or too far off your route, or whatever.
Finally, use Twitter or Facebook or some broad-reach-close-to-public mechanism to ask people "what should I definitely not miss on route X?" or "do you know any hidden gems on route X?". Chances are most of the responses will already be on your list, but you may add a few, or increase the chances you'll visit some of them based on comments from sort-of friends. (That sort of question is not a good fit for SE sites, but it doesn't mean there isn't somewhere better you can ask it, like Twitter. A "please RT" wouldn't hurt either.)
With your list complete, if you want to know something specific, come on back here. Ask something super crisp with a definite yes/no answer like:
And so on.
I don't know if you've already gone on your trip or not, but this information might still be of some future use to you, or anyone else who views this question. There are a number of apps out there that can provide you with a variety of points of interest along a specified travel route, some of which have only become widely available since the last activity on this post.
As others have pointed out, guidebooks, tourism/travel sites, and social media are all excellent resources when planning a road trip. But it can still be cumbersome and/or time consuming to look up all the restaurants, landmarks, historical sites, etc., all along your route, especially when you may not be entirely sure which cities you'll be passing through or how close you'll come to any given location while on the road.
I just returned from a road-trip from Boston down to New Orleans, where we detoured through Nashville, Memphis, and Little Rock on a whim, and I would highly recommend giving Roadtrippers a try. This app is multi-platform (iOs, Android, and web) with a companion desktop webapp.
It allows you to plan out every leg of your journey, select the type of attractions, lodging, dining, etc., you're interested in, and determine how far from your route you're willing to venture. Plus there's a whole host of other features, like saving your trips, favoriting locations, and social media integration.
While Roadtrippers mainly facilitates the before-you-go aspect of itinerary planning, you can also look things up while enroute. However, there are several other apps that do this very well, also. History Here and Field Trip are two of my favorites. Both are GPS location-based travel guides available for iOs and Android mobile devices (see below).
History Here, obviously, is primarily focused on historic landmarks and local lore, while Field Trip specializes in unique and hidden attractions. You can customize either app to notify you when you're near your prefered categories of interest, or you can simply pull them up when you're out and about in a new town.
In each of the apps above, places to visit are compiled from a variety of sources (like local tourism boards, travel magazines, historic registers, etc.), and the vast majority include reviews and ratings from users, as well as from professional review organizations like Zagat.
Since I'm new to this forum, I can't post more than one link in an answer, so you can just search for History Here and Field Trip in either the Apple or Google Play app stores. They should show up at the top of the search results.
What works for some people is a satnav/GPS and set it to point of interest/sight seeing.
Often you can run the route(s) at home and look for all POI near it. That way you can look them up on internet.
But if you like surprises, just set the box on 'museums and sights' and every time something flashes up you make a decision based on the time you have. Friends of mine travel with two different satnavs as they do give different points, enough for them to go through the effort of driving with two, though neither with the voice on.
I am sure by now you can find reviews on the different satnavs based on their points of interest.
Websites such as roadtripradar.com, where you can specify what sort of places you want to find, what sorts of facilities these places need to have when you're there, and how far from your route you're prepared to travel, or Road Trip America - where you can download travel guides - may be your help here.