ok, so this one is a long one, sorry. Hopefully though you find it useful/helpful
I'm assuming you have some ideas of what to see/do in Warsaw since that is your portal city. I've not been there so I couldn't really offer much advice anyway
As you have not been to the EU before, I will offer this advice. Only rent a car when you have to and do it for as short a time as you need to have it. Driving can be cumbersome, painful and expensive as crap. Rentals can be expensive depending on where and what you get. Most offer a diesel option, which is typically easy to find around the EU and slightly cheaper than normal gas. Fuel is rediculously expensive there, most places will run over $9/gal. Remeber they do things by Liter, with most places being over 1.70E/L (
Diesel prices in Europe, European fuel prices, petrol prices in Europe | MyTravelCost.com) Its 3.8L/gal x 1.70 x USD exchange @ 1.35 or around $9-10/gal USD. Thats assuming of course you pay in cash or have a card with no foreign transaction fees. Also we take parking for granted here but you'll find its very expensive to park in a lot of cities, if you can even find a place to park. The Marriott Berlin charges something like 25E/day, in Amsterdam its 55E/day for example. In some places more rural you'll find less challenges/costs with parking but its still a pain.
PS this is an "economy" car there... a Merc A130. POS barely did 80mph floored downhill
Train, subway/tube, taxi or airplanes are your best bet for moving around between cities. When you are in one of the cities, ask if they have day passes for the bus/subway systems. Some do, some don't but it can save you a good bit if you are moving around the city. Also you typically don't have to worry with the zone fee changes as you move from inner city to outter. One thing I found that works well is the bus tours. They can seem a little $$ but make sure you find the one that has the hop on/hop off unlimited within your ticket time option. These ones allow you to get a tour (in english or english via headphones) and move around the city with ease. The buses run every so many minutes through the day and make it incredibly easy to get from point A to point B,C,D,etc. They typically have routes that will take you most anywhere you could want to go in the city.
For the train to Berlin, there are lots of options. There looks to be an express train that takes around 6hrs. I would certainly look at the cost difference between 2nd class and 1st on a ride that long. Food is typically not included in 2nd class, while first is typically pretty nice. Also drink services, power at the seat, perhaps internet access and of course a much more comfy seat might be worth the difference in pricing.
There's literally TONS of things to see/do in Berlin. I've been last year and it was a blast. Where are you staying while there? Some hotels are more central than others and make walking on your own easier.
Definitely make sure to visit this place and some of the other spots around it during the day and its worth going at night too.
Of course this is mandatory in Berlin
This place is worth the walk over too
Going to Munich sounds like a lot of fun. It is however quite far from Berlin. Over 370miles, which is like driving from Dallas to San Antonio and half way back. The train is either overnight or something like 6-8hrs during the day. I'd honestly consider a flight on Berlin Air or something if you really want to head down there.
Other cities within reach via air/train:
Northern area -
Dusseldorf - Great city, lots of history and is a bit of a high end shopping place if you were so inclined to shop. Again, lots of great things to see/do there too and in the area.
Cologne - Roman ruins all over, the Cologne Dome (cathedral) is amazing if you like historic things and/or catholic history.
not one of mine but great shot
Brussels - Really old world city center, great sights and well worth a day trip. Some dang great places to sit and drink beer too in the city center.
Amsterdam - Despite having a rep for being a naughty city (and oh my its earned that one
) there are some great sights to be seen there. Its one of the great cities in Europe for sure. Take a canal tour if you go.
Southern area -
Frankfurt - Fun city, plenty to see and do there. Also a major portal city for flights.
Stuttgart - Lots of fun, plenty to see/do for sure.
If you are down in that area, Neuschwanstein Castle is not too far and certainly is one of the top sightseeing destinations in Germany.
Zurich - Amazing city, though can be a little $$
Innsbruck or Vienna are also within reach.
So that's a few suggestions on places you could see/go
Now the important bits.
Money - All of the EU uses the Euro. Currently trading around 1.33 USD : 1 Euro. Its been going up/down the past few months by a few cents. Xe.com can tell you what its currently trading at, you can evaluate your conversion options on that.
Check with your bank to see if they have any partner banks around the EU. Bank of America for example has a relationship with a few other banks. Here's some other ATM info from them, you can see if your bank has similar stuff.
https://www.bankofamerica.com/deposits/manage/faq-atm-fees.go?js=y
Bank of America United States
Barclays United Kingdom (England, Scotland, Wales, Northern Ireland and the Channel Islands)
BNP Paribas France
BNL D'Italia Italy
Deutsche Bank Germany
Check with your credit cards. See if yours has no foreign transaction fees. If they do, ask if they offer one that doesnt, perhaps with a chip/pin setup. A lot of places will allow you to swipe your card but Europe on a whole uses the chip/pin setup for cards. Some places just don't have the swipe machines so make sure you have some cash.
DO get some cash before you go. BOA will sell you euros at a decent cost, your bank might as well. Get small bills and large, I'd suggest taking at least 100E in cash. Once you arrive get change for a 5 or 10 at the airport. You'll find sometimes ticket machines will only take coins so having 5E in coin (as few as 3 coins) is handy.
Also some places will charge you in USD instead of Euro. Never hurts to ask if they do at food spots, hotels, etc. Make sure you keep the conversion rate in your head, they do make a pretty penny sometimes for providing you the privledge.
Phone Service - All of the EU is GSM for cell phones. If you dont have an unlocked on, you can pick up one for $50 or so on ebay. Look for quad band gsm unlocked phones. Once you are there, you can grab sim cards for carriers. I have often found that the airport SIMs suck and are expensive for what you get. Find a proper cell store and get a sim card. They sell them geared for what you want to use them for so make sure you tell them the calls you will make. Vodafone is a popular place, also T-mobile has coverage in Germany. I carry a basic just normal phone with me and my smart phone. There's plenty of free wifi in places to use my smart phone on and the plain phone allows me to not use my allocated money on the SIM for data, just simply for calls/txts. Vonage, Skype and Tango allow you to make free wifi calls to the US from overseas to users with those apps in the US. If you are calling a land line, just get a SIM that is specifically set for calling the US.
The only other tid bit of advice. Take as little as you can with you. Packing in as few and small bags as you can will save you tons of possible pain points moving around places. I travel with a 21" US carry on bag and a backpack. You'll want to be able to carry your bags by hand if necessary as some places don't really have elevators handy. Also a lot of the time, you really dont need 1/2 the crap you take
I often take a small but durable soft side duffle bag with me in my bigger bag. There's been times I've taken most of my clothes out of the big bag and put them into the duffle so I could managed to bring all the random crap I bought home
Hope this helps, let me know if you need specifics or anything at all