Vienna to Prague; Prague train station to Old Town by taxi or by walking?

Have you tried using Google Maps? It's a great tool for questions like these involving distances.

Google "Prague Train Station"...look at the google map, put in "Old Town Prague" to get directions from the station (or better yet, put in the first landmark you want to see like Wenceslas Square). Click the "walking" icon. You'll see it's more or less a 15 minute walk (1.5 km). You can even print out the walking map and take with you. You'll also see subway stops on the map as well - that's also an option.

Prague train station Nadrazni Hlavni is on the edge of the old town, easy enough walk to the heart of the Old Town Square.
https://www.google.co.uk/maps/dir/Prague+Main+Railway+Station,+Wilsonova+8,+110+00+Praha+2,+Czech+Republic/Starom%C4%9Bstsk%C3%A9+n%C3%A1m%C4%9Bst%C3%AD/@50.0836176,14.4253187,16.24z/data=!4m14!4m13!1m5!1m1!1s0x470b9493dbd624df:0x2743b9a02dbd7d76!2m2!1d14.4353033!2d50.0831937!1m5!1m1!1s0x0:0x97ef2407c21e72c4!2m2!1d14.4211874!2d50.0875692!3e2
this gives you an idea of the walk and really getting a taxi is of little help as the main areas are pedestrianised.I would walk from the train station to Wenselas squre ,only 5 minutes and walk down the lenth of Wenseslas Square (It is a wide boulevard and not a square) and into the heart of the old town, just follow the Brown tourist signs or indeed the crowds. all easy enough

btw the timing on the google maps is well out ,I would say 10 minutes or a little more to Old Town Square.
If you do want a Private tour try this guy.
http://livingprague.com/
Jason might even be able to meet you at the train station and start a tour from there, he will adjust the tours to your needs and can include a meal stop.

A day trip to Prague from Vienna with two small kids (9 hours on the train!) sounds dreadful. At least spend the night, or maybe choose somewhere closer.

Sort of a long day trip. I think I would worry more about my kids attention span on two 4 hour train trips. With 5 hours in Prague + time to and from train stations (no matter how you do it); that's an 8am until 10pm trip to one of the most crowded tourist destinations in Europe. Personally I would go the opposite direction, especially with kids.

If you decide to use a taxi the key to the best experience in Prague, as in most cities, is to call a reputable company and have them send a car (as opposed to hailing, taxi stands and letting the hotel or anyone else call for one).

This is one reputable company, City Taxi - tel. 257 257 257, www.citytaxi.cz ; but there are others. You can find names and reviews on line, pick a couple and take the names and numbers with you.

Or do what ever Unclegus says, as he is "The Man" when it comes to Prague.

I was looking to take a 7:00 a.m. train from Vienna and arrive about 11:00 a.m. Then I would leave Prague either 4:00 p.m. or 5:00 p.m. It certainly will be a long day, but I would encourage the kids to take a nice long nap(s) to/from Prague.

We found the train ride from Vienna to Prague to be pretty rough. The trains are slow and old==not new and fast. Although we were doing the trip in April, the air conditioning was poor and we were very uncomfortable.
It's just not a good day trip.

If you want to do a nice day trip from Vienna, take a bus, train or hydrofoil boat (in season) up to Bratislava. It's only 39 miles from Wien, but a world apart. Everyone there is speaking Hungarian and English, and it's quite a beautiful, vibrant, high income city.

How long ago did you go? I heard that the Railjet's are nicer trains. I was also considering buying 1st class tickets, so the kids have more room in their seats to lie down and nap (perhaps even empty seats would be available, so they can sleep undisturbed).

We took a Railjet from Vienna to Prague in August 2015, and it was a very nice, air conditioned modern train. I recall the trip was just a little over 4 hours.

You want a Railjet, not an IC train. Absolutely no need for 1st class. You can look at photos of train seats on the ManInSeat61 website.

Its really hard to tell the difference between 1st class and 2nd class on a RJ Train. They are good clean trains. If you get on the right RJ direct train then its a mere (advertised) 3:59. Rates are about $22 in advance and $70 at the station. I said 9 hours RT thinking door to door. So your 5 hours in Prague (returning on the 4pm train) is going to change to something closer to 4 hours by the time you get to Old Town and then get back to the Train Station for the return trip; especially dealing with kids.

Reality check! 8 hours of boring train ride (not counting getting to/from the station) for 5-6 hours in strange city with a different currency and presumably a lunch break? And a picnic supper on the train back?

Are you sure this is a good plan for you?

The OP said he has "done" Prague before so it's not going to be some strange city. It's so darn touristy and compact that I don't think it'd be all that hard to navigate even if it was "new" to someone. Stopping at an ATM to get some cash is an almost insignificant barrier, easily remedied. I've done these kind of day trips and they were still fun albeit a bit rushed because I like to have long, leisurely meals and cafe stops (but I was traveling alone or with another person, not with small kids). Adrenaline often takes the sting out of being tired, but long days like this are tiring. But you can sleep on the train. If I had to do it over again, it would have been great to stay overnight just to make it a bit more manageable (that comes with its own issues though because some small luggage gets involved).

If the OP and kids are up for it (only OP knows the kids' tolerance and flexibility), just prepare for a long day and have fun. Maybe pack something to eat, because sitting for a leisurely two-hour meal will really bite into your (rather short) sightseeing time. I think the previously mentioned Bratislava would be a fine substitute as well. Good luck and have a great trip!

Perhaps I should spend one evening in Prague, instead of trying to "do" Prague (albeit, Old Town only) in about 5 hours. The kids are young, so their tolerance may be tested. Afterall, to "do" Prague in 5 hours requires catching a 7am train from Vienna, which means that the kids would need to wake up at about 5:30 a.m.

Also, in addition to local currency, does anyone know if the tourist shops/restaurants accept euros?

Also, in addition to local currency, does anyone know if the tourist shops/restaurants accept euros?

Even if they do, I wouldn't try to use Euros. You'll just get a horrible exchange rate - why bother when there are tons of ATMs around? Use a credit card or local currency (koruna), just like any other country.

How old are the kids? Some travel real well and are troopers, and some don't. As a relatively young (early 40s), fit and flexible person who likes to run around all over the place, I even find these whirlwind trips exhausting. I do them still but I only do them with a friend with similar disposition and energy level who doesn't mind that kind of travel. The rule of thumb for me is I try not to spend more time "in transition" to a place than actual on-the-ground time. You'd be surprised how quickly the 5 hours will fly by and how long that 8 hours on the train will seem. I would favor spending the night - at least you can get some sleep and soften some of the pace. If this were just two adults traveling, it would seem much more likely to be a good experience than going with two small kids. The tip off was your initial comment about just walking from the train station - that's a pretty low bar and just the start. If the first 15 minutes of time in Prague may be that difficult, then 5 hours of walking and trying to fit everything in might be grueling.

yes you will be able to use Euros in many places but not all but as Agnes says you will get a very poor exchange rate, most places will take credit cards

Hi,

In Prague you can do this: the shop staff will most likely know what the exchange rate is regarding the Euro and Czech Krone. If they calculate that and say what the cost is in Euro, pay them in Euro exactly (if you have the change to do so ) or as close as possible. . If it costs 4 Euro, and closest you have is a 5 Euro bill, just pay it, forget the change.

Day trip with 2 young kids? 8 hours on train roundtrip? Personally I would not do it. But if you insist ... Honest taxi service - one of the best is AAA - honest and drivers speak English. I would recommend walk. It is about 20 minutes and on the way you will see a little bit of Prague, among others Wenceslas Square. If you want to save your energy for Old Town take a subway /Metro/ from Main Train Station to Mustek or Staromestska. It is cheaper and very likely faster.
Usually you can pay with Euro in Prague but it will cost you more. Estimate amount of crowns you will need and take them from ATM.