If I were writing a postcard home from a sunny city, I would normally put the adjective just before the proper noun like "sunny Berlin". What should I do when it's The Hague?
It is all very nice that sunny The Hague gets violent comments and down-votes from the seemingly inflexible prescriptive crowd, but the fact of the matter is that proper names are not always to be treated as just any other word.
For those that think that The Hague should be parsed as the Hague, think again. I somehow wonder if you also think of Las Vegas as las Vegas, and send postcards from las sunny Vegas?
If you want to convey you are spending your holiday on some sunny plains, that would make perfect sense, but the city is Las Vegas, with the article being a part of the name.
Since Den Haag seems too hard to pronounce, it has been translated to The Hague, which is fine. But no Dutchman will associate hague normally with the city - the The or Den is an non-removeable part of the name.
It may be noteworthy though slightly off-topic that den is not an nominative either - it is an inflected article with a locative meaning. A better English translation of the name would be At The Hague.
Now, assuming that the locals would have some idea on how to use their city names, I can tell you that in Dutch, one would send a card from zonnig Den Haag. Splitting up Den and Haag is simply inconceivable, and makes as much sense to a Dutchman as splitting up New and York.
Actually, in Dutch we do tend to be sticklers for keeping the article with the proper name in some cases. One of the leading quality newspapers, De Volkskrant, published their style guide ages ago, indicating very clearly that the full title of that style guide was:
Het De Volkskrant Stijlboek.
Which would roughly translate to "The The People's Paper Style Guide".
Now, as for The sunny Hague, I would read it as if you were camping near some bushes, and it is nice weather. Feel free to use that form if you think the recipients of the card understand it better than sunny The Hague, but unless you send postcards from New sunny York as well, it will be seen as strange by people that actually know the city and understand it's actual name.
In the end, I will respect anyone's free choice in this, but I resent the vehement telling-off of people that respect the integrity of geographical names - especially because splitting the name up only seems to happen in random cases, because the "splitter" confuses part of the proper name with the nominative definite article...
Greetings from The sunny Hague!
Greetings from New sunny York!
Saludos desde Las soleadas Vegas!
Greetings from Los sunny Angeles!
I won't forbid anyone to write those things on a holiday post card, but please don't put down the ones that don't :)
And actually, this whole discussion is moot as chances are you will never use sunny and The Hague in the same sentence...
Greeting from the Hague. Its sunny here today.
I would say that, since "The Hague" is the proper name, the proper form is "sunny The Hague". Since you're dealing with a name (a proper noun), "The" isn't treated exactly the same as the definite article would normally be treated.
The answer is "Greetings from a sunny Hague".