Should I buy train tickets in advance & the round trip at once?

• You could fly into Frankfurt, it is nearer to Heidelberg. Then fly out of Munich.
• Yes, buy tickets in advance, its cheaper. From the official DB (German Railways) website: https://www.bahn.com/en/view/index.shtml This will get you "self-print" tickets
• Return (round trip) tickets are sometimes cheaper. Look on the DB website.
• Munich has dozens of stations. There is one at the airport called "München Flughafen" (Flughafen is German for airport). The main one in the city centre is called "München Hbf". The main station in a German city (where the long distance trains stop) is always called "Hbf" (= Hauptbahnhof = main station)

When looking up trains, just look up the complete trip, for example "München Flughafen" to "Heidelberg Hbf" (plus date and time). This will always find the quickest route.
Click on "show details to and list all the trains and changes of train needed.
Click on each train number to show the stops for that train.

For a beginner's guide to train travel in Germany, see here: https://www.seat61.com/Germany-trains.htm

You really don't buy round trip rail tickets, you buy 2 one-way tickets. There is no discount for round trip. You can of course buy, a round trip tickets (buy both at the same time) but you are essentially buying 2 separate tickets.

You don't say when this is going to occur. Looking at July 25, you could save 100 to 130 EUR (for 2 people) by buying nonrefundable tickets now. Problem is you cannot be sure your plane will arrive on time, and if you are late and miss your train, you have to buy new full fare tickets. Therefore, you should allow 4 to 5 hours after you land to book the train. So if you are supposed to land at 8 am, book a train for the after noon. Buy the ticket from Munich airport to Heidelberg. If you land on time, you can take any S-Bahn train to Munich Hauptbahnhof (main station), store your luggage in a locker and tour around Munich for a few hours, then get your scheduled train to Heidelberg. The S-Bahn goes every 10 minutes by 2 different routes to the Hbf.

Another option, with certain airlines including Lufthansa is to book a Rail&Fly ticket. you pay a set fee, about 34 EUR per person and you can take any train after you land to Heidelberg.

The return ticket to Munich should be bought now to get the nonrefundable discount.

Buy tickets at www.bahn.com
Lufthansa Rail & Fly, https://www.lufthansa.com/nl/en/lufthansa-express-rail-fly

Sam,
We are arriving on may 16th. and we are flying Luftansa! I will try your link for that now. thank you!
I called Luftansa (and spoke to the snippiest rep). I can get 2 one way tickets from Munich airport for $76. If I'm looking at the DB site correctly, our tickets should only cost $66 if I buy them myself. She did say I could change the time on the tickets when we arrive but she couldn't tell me where the train station was in relation to the airport.
Your feedback???

Chris,
I responded to your post but it hasn't popped up. So, thank you. Flying into Frankfurt was considerably more expensive. I was also concerned about the possible issue of a late plane. Thank you for the lesson on using the DB site. I will refer to it each time I use it.

The Rail and Fly is the better deal, at least for your arrival day. Those $66 tickets (59.80 EUR) are train specific and nonrefundable. A late arriving inbound flight and you would lose them and have to buy new full fare tickets. Either that or leave a big time allowance, and still no guarantee if the flight is severely delayed. The Rail&Fly allows you to travel as soon as you clear immigration and get your luggage. Extra flexibility is worth $10.

There is a train station at the airport, just follow the signs. It is an S-Bahn (commuter train) that goes to the Hbf (main station) every 10 minutes.

Thank you Sam!! So there is a train at the airport. I purchased the rail/fly and hope we are able to take the 8:44am since there is only one change. I appreciate all your help. I will now work on our return train back to Munich on the 19th.

Sam,
So sorry to bother again. I am looking at the Heidelberg-Munchen may 19 at 10:10-13:27. It doesn't appear to let me book both myself and my son at the same time (Book me - Book others). Is this correct? Also, should I purchase the reserved seat for 4,50Eu?
Thanks again!

bilezmom, Right at the very first page, where you enter the "from" and "to", it asks the number of travellers (adults and children, child is 6-14). If you leave this blank it assumes 1 adult.
"Ticket for another person" only applies if you aren't travelling (if you are paying for somebody else).

Rail tickets, unlike air tickets, are usable by anyone. Normal (station bought) tickets do not have any names on them. The only reason it asks a name for PDF tickets is to stop you printing a second copy and giving it to someone else. As long as your name matches, and the total number of people is correct, you are OK.

The reserved seat for €4.50 is a good idea. For two people, it ensures you get two seats together.

Thank you, Chris. I found it! I will also add the seat selection and the transportation ticket at the arriving city.