hi , i will b travelling to vienna-salzburg-innsbruck-munich-berlin-prague and back to vienna this summer (jul-aug) with my 1 yr old and a 5 yr old with friends.we r planning to rent a car so its easy travelling with kids. we r 4 adults so will tht be better than trains? any other suggestions? apartment or bnb recommendations?
So, you have 4 adults and 2 kids. That means you need a car or mini-van large enough for 6 people, plus their luggage. You will need car seats for those children too and probably a stroller for the little one. Check gas prices too, as I think it is running about 9$ a gallon. Trains might be a better and easier option for you. Check all the prices to see which one will work better, especially with travelling in more than one country. Some rental agencies don't like this or won't allow without extra fees.
If your goal is to mostly see major cities, I don't think a car is the best option. Driving into these cities is difficult, parking is expensive, and you won't be using the car while in the cities. Unless you want to spend time in small towns in the countryside, I'd consider trains for most if not all your trip (the only place I'd really consider the car is Switzerland, and even there it's not a necessity).
I would recommend train. I have traveled in Europe three times with my little kids, always using trains. Car seats are a pain, much easier to take the train. Kids typically travel free on the trains, or a very small fee. Also, most little kids love the train, it is a fun ride for them. Some trains even have changing tables in the restroom, making it easy to change the diapers. Either Sweden or Switzerland had trains with changing tables, can't remember which one.