Paris, Amsterdam, Berlin, Venice, Austria

As far as cheap flights to Europe it depends a lot on where you are flying from.

Did you mean hostels or mean angry people (hostiles)?

Take a look at monasterystays.com. The monasteries are often lovely historic buildings and most have renovated rooms with en suite bathrooms. Less expensive than most hotels and often centrally located.

In order to get the best advice from this forum you’ll need to be more specific as to where you’re flying from, where you want to go, what time of year, for how long and what your interests are. Europe is a big place and the areas you indicate in your header are far apart from each other.

My first budget tip is that moving around costs money. You will save money by seeing fewer places. How long is your total trip, meaning, how many nights do you have in Europe? Remember that you land the day after you leave the US (assuming that is where you are starting from), that the day of arrival is often a jet-lagged haze, and that the day of departure is taken up with getting to the airport. So, you likely have fewer sightseeing days than you think.

Yes, if you want airfare assistance you have to tell which airport or airports you would be leaving from. But you also have to check Kayak, Google Flights, etc. yourself. Airfares bounce around constantly and can be gone in an hour, although from some places they are more fixed.

Be sure to look for "multi city" or "multiple destinations" rather than two separate one ways, which can be much more expensive (or not, depending on the airline). If a round trip is "cheaper" than a multi city, be sure to add in the cost of getting back to your origin airport - and remember you lose time doing this too.

When it comes to flight prices, the rule is that there are no rules. I'll repeat my favorite example. In March 2017, I was looking at flights from New York to Europe for May 2017. According to the "experts," that's too late to get a good fare. Well, NYC to Zurich was $349, nonstop with a choice of airlines (not a typo - three hundred and forty-nine dollars!). Then I looked at Geneva, for the same dates. Nonstop flights were about $1200; flights with a very long layover in Casablanca were about $650 (Royal Air Maroc was having a sale); and flights with a more reasonable stopover started at about $700.

Why was Zurich so cheap? Why was Geneva so much more expensive than Zurich? Your guess is as good as mine.

More recently, my sister just booked Washington to Barcelona for about $580 - with only three weeks advance purchase! And my other sister was able to pay $400 per person, nonstop, from NYC to Prague, in the middle of the summer, by buying from Expedia instead of the airline, which wanted to charge twice as much (still not a lot for the time and destination). Again, you can't count on these things, but you can be ready to pounce and buy them when you see them. If you are leaving from a secondary airport, you may not be able to get any bargains.

Similarly, if you want specific recommendations for accommodation, we need your budget in euros ("not too expensive" means different things to different people) and your needs. Can you have a bathroom down the hall? Can you have twin beds or do you want a double bed? Do you need an elevator? etc.

In addition to looking at listings in Rick's books, you can look at EuroCheapo, for both lodgings listings and budget tips: https://www.eurocheapo.com/

I see you listed 5 cities you plan to visit in May 2019. How many days will you allocate to each city and what is the length of your entire trip? Rome, Italy , Berlin, Germany, and Vienna, Austria would give you cheaper airfare compare to the other cities. You can do an open jaw flight which is fly into Rome and fly out of Vienna to go back home. I would do Rome instead of Venice then from there go to Paris, Amsterdam, Berlin, then fly out of Vienna. Venice can be visited on a future trip.

Actually, from many places in the US Amsterdam and Frankfurt are the cheapest places to land in Europe, so it really does matter where you are flying from.

Does your home airport have Norwegian Air Shuttle or one of the ultra budget European airlines flying into it? That's the cheapest way to get to Europe. Depending on the day of the month, flights can be under $500 in the upcoming months. You can catch EasyJet or RyanAir from many gateway cities in Europe to most any other European city for $100. I recently flew from Dublin to NYC area for $158.
You really need to prioritize where you're going. Remember that the first and last days of any trip are wasted days. And every time you move from city to city, that day is essentially wasted. It all comes down to how long your trip is going to be and what your budget is
I too believe in flying open jaw into one city and home from another.
We try to travel to cities that are relatively close together and cities that compliment each other. An example would be Rome, Florence, Venice. Or Paris-London. Or, Munich, Salzburg, Vienna. Or, Prague, Vienna, Budapest. Or Amsterdam, Brussels, Paris. Your itinerary noted is not easily traveled between by train and is not very efficient. Decide where you need to go and then go back to the drawing boards.

"...to do this budget-wise." How many of the amenities are you willing to forego...A/C, elevators, staying only in 2 star hotels or Pensionen in Austria and Berlin? Of the cities listed here, Berlin is by far the cheapest. The fewer expectations you have as to amenities, the cheaper the accommodations, and I'm not referring to hostels as you have precluded that option.

I have edited the post a bit. The most expensive part for us is getting out of the Mid-west. We have to add at least a day or more of travel time because of that. It would be good if we could have a base location (or 2) but it's been hard to figure that out. No less that 3 -4 days in each location, except Amsterdam & Venice, those would be shorter stays. It would be nice to spend nights where we are visiting without having a lot of travel to get back to our lodging every night. A bathroom in the room would be preferable along with the location of the facility as we'd like to enjoy our time in that location & not be worried about getting "home". Stairs are OK as we'll use backpacks. Big cities are not our thing so sidetrips would be planned. However, being in the city in the evening for dinner & a show would be good. Paris is the first priority & all others are secondary. Austria would be amazing. Thank You so much for your insights, it's overwhelming when you're inexperienced.

How many nights will you be able to spend in Europe--not counting the night on the plane?

"Shorter stays" than 3 or 4 days in Amsterdam and Venice are not, in my opinion, a good idea. It sounds as if you are planning a very short trip (which I realize is all many travelers have time for), in which case you'd do far better to rein in the geographical extent so you are not spending so much time on trains, buses and planes. Unless you happen to be traveling through the Alps (and Swiss trains are very co$tly), that travel time is usually a dead loss as far as sightseeing goes. Even if you're not traveling far at all, every time you switch hotels it's likely to cost you half a day. Long-distance moves and those including flights will mean even more time lost. Then to spend only 1 or 2 days in Amsterdam or Venice? The cost of each hour of sightseeing time is going to be very high indeed.

I suggest you start by picking up a guide book to the country that is your #1 priority. Visit your local library or buy a used copy online if you want to. Skim through that book. Aren't there a lot of places that sound great? You don't need to go to five different countries to have a great trip. Then look at a map and see whether you might be interested in somewhere in a nearby country and study it. For example, Austria + Venice would be a good combination.

The trip length will be about 3 weeks.

We are coming from the Midwest, so the nearest large airport would be
Minneapolis, Denver, Sioux Falls, Rapid City, SD.

Consider Iceland Air which operates out of Minneapolis and Denver. Any airport in South Dakota is not a good choice - the state and its cities is too small and sparsely populated to get a good price. You should concentrate on large population markets where airlines compete for business, including budget carriers.

Where do you live exactly? Are either Minneapolis or Denver convenient enough for you? I assume Chicago is out of the question, correct? Obviously, you will have to take into account any additional cost of getting to the selected airport - whether that means mileage, parking for the duration of your trip, hotel stay the night before or day after, or all of the above (it sounds like driving to the airport is your only option, right?).

With 3 weeks you can cover a reasonable amount of ground. But is that 19 nights in Europe or 21? I still wouldn't try to cram in all five of your original destinations, as spread apart as they are. I'd pick some of them and try to fill in the gaps (if there are any, after you look at all the sightseeing possibilities) with nearby spots that are very worth seeing, especially those that do not require you to switch hotels.

I live in St. Paul area, I agree with checking flights with IcelandAir. Though for me recently, Delta has been just as competitive without the layover in Reykjavik. I strongly recommend watching the RS tv shows for your destinations to help you solidify where you'd like to go. Even if you've seen some of the shows, I'd watch again. I typically am able to spend less on lodging in Europe than in the U.S. Of the cities you list, Amsterdam accommodations were the most expensive for me. Spain, except for Barcelona tends to be very affordable.

It would be nice to spend nights where we are visiting without having a lot of travel to get back to our lodging every night. A bathroom in the room would be preferable along with the location of the facility as we'd like to enjoy our time in that location & not be worried about getting "home". Stairs are OK as we'll use backpacks. Big cities are not our thing so sidetrips would be planned. However, being in the city in the evening for dinner & a show would be good.

This is very contradictory. You say you want to be in a central location in some of Europe's biggest cities, but that you're not city people and want to do day trips as a result. Why would you want to pay to stay centrally (which will cost more) when you don't want to be in a big city?

Paris is a must so sure, stay in Paris, but for Netherlands, why not stay in a smaller, more charming city like Utrecht or Haarlem? It's easy to get around to visit Amsterdam for the day from either of those locations.

Why is Berlin one of your choices? Why not travel to Munich and stay in Bavaria in a charming town, perhaps Salzburg right across the border in Austria? Because Berlin is huge and sprawling and not well situated for day trips to other places and is very much a big city.