My husband and I will be renting a car from Frankfurt Airport in 2026 in May and will spend 12-13 days visiting Rothenburg, Nuremburg, Prague, Poznan, head back toward Frankfort for flight home.
We will be visiting town/city in Germany (Rot Am See) and Poznan where our families came from. Any advice on itinerary or days in each area? From Prague to Poznan suggestion to stay 1/2 way is Jelenia Gora and on the way back to Frankfurt, Erfurt Germany? Thank you kindly for any tips!

Have agreed with the hire company for the car to leave Germany?

We have not booked our car rental yet but 12 years ago we drove from Frankfurt to Prague with no issues.
Thank you

There are tons of possible stop overs. All depends on your interests.
Tell us what you afe looking for and we can make some proposals.

Where are you coming from? If you are crossing multiple times zones it is not advisable to drive immediately after landing for at least 24-36 hours. I'd train to your first destination and pick up rental from there.

Are you flying multi city (in one airport, out another) or round-trip? If so, you may have a hefty drop off fee for car. Depending on your itinerary, train may be the way to go. If you are round-trip, you will need to figure a plan to get back to that originating airport - which will take time. If you have not booked flights, I'd strongly consider flying multicity.

As for everything else... is this a sightsee trip? I can't decipher if you are wanting to research your family links or simply see the towns/areas they are from. If sightseeing, get some guidebooks to determine what you want to see depending on your interests.

Figure transit/driving times into whatever plan you have as changing hotels and transit eats into your time. Is that 12 days on the ground or does it include your flights? If the latter, you only have 10 days and are planning on covering a LOT of distance.

I'd advise against using Google for driving research as it does not accurately account for factors and are underestimated. Research rome2rio and viamichelin.com. If you decide to supplement train travel, a great resource is seat61.com

Agree with bilbo, you might have a problem in taking the car out of Germany. I have rented cars where it was forbidden to take the car into Poland. Admittedly it was some time back but you should still look into this. There should be no problem in renting cars from Poland (and Czechia).

Lavandula

SIXT conditions for cross border car rental, others have similar rules.

Cross border rentals and territorial restrictions

Territorial restrictions

The vehicle selection can restrict travel to certain countries. For a description of these restrictions on admission, the countries are divided into three zones.

Zone 1: Andorra, Austria, Belgium, Denmark, Finland, France, Germany, Gibraltar, Great Britain, Ireland, Italy, Liechtenstein, Luxembourg, Monaco, Netherlands, Norway, Portugal, San Marino, Sweden, Switzerland, Spain and Vatican

Zone 2: Croatia, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Slovakia and Slovenia

Zone 3: All countries which are not in zone 1 or 2.

Sports & luxury cars may enter only in Zone 1 countries. Audi, BMW, Mercedes-Benz and Volkswagen cars up to group L*** are allowed to enter only in Zone 1 countries as well as Poland, the Czech Republic, Slovenia and Croatia, while X*** cars are only allowed to enter in Zone 1 countries. Vehicles of all other brands may enter only in the zones 1 and 2.

Trucks, vans, people carriers and minibuses of all brands may only be driven in zones 1 and 2, except Hungary.

Entry into any country in zone 3 is not permitted.

The local transport of the vehicle by ferry is permitted in compliance with the above-mentioned entry restrictions. Damage to the vehicle during the crossing will be covered according to the protection booked in the rental contract.

In case of offence against cross border and territorial restrictions all liability restrictions lose their validity. Only the protection of the liability insurance remains.

I have never been to Jelenia Góra, but Wrocław is only a 4 hour drive from Prague.
Not knowing your interests hard to say which one you would find more interesting.

P.S.I don't understand recommending a train site to someone who is renting a car.

If you had read my reply more thoroughly, I suggested that OP not drive the first 24-36 hours if they are crossing multiple time zones due to jetlag and to train to their first destination upon arrival, then rent a car. And I used the word "supplement [the] trip" with train travel as well. My suggestion is to give them options as well as for *safety.*

OP, your post here was delayed significantly so I was unaware that you have made this trip previously? What did you see/go to before? How long? How much are you wanting to see again?

These details are only being asked to gain understanding of what your goals are this trip are compared to your previous one.