The bod has a 'long weekend' (four days, at a guess) he'll maybe struggle to do Calais, Berlin and the Baltic States... Unless he gets his skates on.
As I said, I took a week, and a 2cv has to be much slower than anything this side of a postie bike.
I have, perhaps like a few others, done rides "just because", perhaps that is the OP's motivation.
Over a long weekend with a yen for the north, I'd perhaps do Berlin. The Baltic States are a bit far - TBH I was thinking more like near Poland, only another few dozen kms.
Perhaps the Baltic States deserves a greater time commitment too, but soon. They are changing very rapidly .
I also got to see Berlin before the wall came down. When I was last there a couple of years ago, they had just realised there was almost no wall left and had to arrange for it to be preserved.
I'm a bit of a Len Deighton fan, so it was nice being able to have a poke about some places he mentions which had been off limits on previous visits.
The Stalinallee, nee Frankfurterallee (don't know its current nomenclature) was interesting too - great monstrous soviet show boulevard, but the little Hinterhof behind had lots of nice little apartments, presumably for the privileged Apparatchiks, unlike the metal framed workers social housing near a very old fashioned restaurant, eating some great Kartoffeleintopf mit Bocki, with some decent Dunkel Bier. Lovely atmosphere, now.
I own personal "pointless" trip would be to some pleasant corner of France, booked into a small family hotel with a few Michelin *'d restaurants with easy reach. Perhaps include a few vinyards to visit during the day.