Well, to bring a provincial German perspective to this US focused thread. In Germany, royal events from Britain are regularly covered not only in the "old ladies magazines" (of which there are still lots) but also in the mainstream media.
Germans and Britains have a long and tangled history (no, I won't mention the war), and many Germans know that many German princesses married into the BRF.... and that they changed their German family names (Battenberg, Windsor, Teck) under George V to English names and titles. (I read quite a lot of books about British history written by British authors, and when they say "Teutonic" or "Hanoverian", it's always negative.... i.e., what's great about their royals is British, what's weird about them is of course Hanoverian or Teutonic genes LOL). Our own aristo families are no longer ruling or reigning anything and are no longer well-known, except for some colourful birds like Ernst August or Gloria von thurn and Taxis, but people who follow these German families know that most of them are cousins of QEII or the DoE or both. And that may be the reason that interest in the BRF took over since we have no royal glamour and ceremonies any more.
Memories of the Imperial court and its celebrations have long faded away but when you see pictures of aristo weddings in Germany, the women are dressed in the British style with wacko hats and pastel colours, far removed from normal German dress code. BRF style has come to mean aristo style in general.
But in Germany, Grace was very popular (I wrote about it in the latest Grace thread). She made Monaco respectable (and she had a German mother!), she was glamorous, and her influence on style and fashion in the Fifties made her important for her generation - which is probably the generation that bought most of the gossip magazines.
Then Queen Silvia was and is seen as "ours" somehow. Her children, especially Victoria, are always in high places on the "most popular royal" lists (I don't know how they poll that but German gossip magazines seem to love these lists).
The Norwegians are popular, too. Most Germans like Scandinavia and its style, it's seen as "like us but somehow cooler", and MM was covered for a while quite intensely when she was new on the scene.
People are also aware of our neighbour countries RFs, Denmark and Netherlands very much, Belgium and Luxemburg too, although probably less. I guess if you asked the average German to mention five European RFs, they'd say: British, Swedish, Danish, Dutch and hm, Norway....? and would probably know the Queens better than the male family members. They're more visible.
Since we were at war with all of our neighbours on and off for centuries (European history is a history of conflict) and all look at each other with ambivalent eyes (yeah, we're all Europeans and stick together .... but look what nice nick names we have for each other!), there are sometimes national stereotypes in the background. Oh those fresh faced and nature-loving Norwegians...
About the Netherlands - some German princes in the Dutch RF may have played a role, but there's also this feeling of nearly-cousins. For people with historic memories, there's also gratefulness for housing the embarrassing old Kaiser. It was a long time ago but he was our last monarch, and if the Dutch had not given him protection and a place to stay, who knows what he would have done? There was and probably is also admiration for the strong Dutch queens, Juliana and Beatrix, and now the different-but-interesting Maxima.
The model of "royals on bikes", i.e., unassuming and democratic, is emphasized about these monarchies although they're of course also very rich and by no mean just normal citizens.
For past monarchies, German who are interested in history remember of course Sisi thanks to the movies, marketing and one very good biography about her (by Brigitte Hamann). There's a whole genre of popular history books about the Habsburg monarchies and minor German houses, started by Thea Leitner, focusing on the fate of the women (sold or manipulated into marriage by their parents and/or politics, more or less). People who read such books know that German and Austrian princesses had a tough time in Russia, Great Britain, France and Naples, and that's again a kind of link to the past.
Poor Anne of Cleves, imagine coming from Cleves and being laughed at by the court of Henry VIII! Poor Alix of Hesse, imagine being hated by the whole Russian people! Poor Sisi, imagine coming from liberal Bavaria to the stiff court of Vienna! Poor Elise, imagine coming from Catholic Munich to arrogant Protestant Berlin! Poor Princess of Anhalt Zerbst, turning into Catherine the Great... no the pity party won't work here!
There are dozens of such books on my book shelf, and I'm not the only one who likes to fill the gaps of male-centered history by the fates of the women.
Btw, our own past of Tiny Principalities that ended officially in 1918, is still palpable in the federalized structure of today's Germany, and the strong regional differences.
Maybe I'm wrong in my impression that today's monarchies and royal families are still quite popular in certain circles of the German public for tangled historical and sentimental reasons - but politically, for most Germans, they're completely irrelevant and we can't imagine bowing and scraping to a monarch ... albeit when William and Kate come to Germany, everybody would love to meet them, even if they had to bow and scrape a bit. But 99% of Germans, I'd say, are very happy they don't have the Hohenzollerns or any other ruling house representing them any more.
And the BRF is also here the most popular RF and most people know them, while you have to have an interest in the topic to know the others.