The use of articles is a complex topic and can cover whole chapters in grammar books. I'll just go through your sentences.
Several million visitors a year are attracted to the ski slopes of the Alps.
There's a definite article in front of “ski slopes” because the sentence is about a specific group of ski slopes: the ones in the Alps. If there it was just “∅ ski slopes”, it would mean “some ski slopes [but not all of them]”, and then the complement “of the Alps” would sound strange since it wouldn't be defining a set anymore. “∅ ski slopes in the Alps” would be fine; in that sentence, “attracted to the ski slopes of the Alps” implicitly designates all the ski slopes in the Alps, while “attracted to ∅ ski slopes in the Alps” makes it clear that only some ski slopes are attractive.
While we're at it, why “the Alps”? Most proper nouns don't take an article. But most plural proper nouns take the article the, and mountain ranges are plural (there may be exceptions but I can't think of one). The Alps, the Andes, the Himalayas, … Individual peaks normally don't take an article: Mount Blanc, Mount Everest, Aconcagua, …
I went to ∅ Buckingham Palace today. It was great.
I took the train to ∅ London and then the underground to ∅ Victoria Station. It’s a short walk from there.
If you ever go to ∅ London you must see the Tower of London and the Tate Gallery.
The default rule for proper nouns is that they don't take an article. I highlighted a few more — London doesn't take an article.
Then we have ∅ Buckingham Palace vs. the Tate Gallery (the Tate Gallery does take an article). As a rule, people's homes (including official ones) don't take an article: ∅ Buckingham Palace, ∅ Mansion House, … Many other kinds of buildings don't take an article when their name is of the form <specific designation> <building type>, for example churches (Westminster Abbey), hospitals (Mount Sinai Hospital), and stations, airports and the like: ∅ Victoria Station, ∅ Heathrow Airport, ∅ Boston Harbor, ∅ British Museum (the former tube station), … But museums and monuments do take an article: the British Museum (the museum), the Tate Gallery, the Washington Monument, the Tower of London…
The Tower of London takes an article for another reason: it's phrased as a common noun with a qualifying complement. It's hard for the X of Y to lose its definite article, even if the clause as a whole becomes a proper noun. Likewise the Port of London, the Port of Dover take an article. But there are exceptions, for example Port of Tyne. Similarly, it's the White House, because white is an adjective here, not a name, so it's more like the house of X, although it's still a proper name so House is still capitalized.
After his wife’s death he left ∅ home and joined the army.
John himself doesn't go to ---- church.
Home and church in these contexts are general concepts and take the null article. It's rare for home to take a definite article (usually, in contexts that would require it, a word like house is used instead); the church means a specific building (“the church is being renovated”), and the Church is a religious institution (out of context, usually the Catholic Church).
There will always be a conflict between the old and the young.
“The + adjective” means “people who are X”. More generally, it can mean the elements in an implicit category that satisfy the adjective, e.g. “predators catch the sick and the wounded” (implicit category: animals).
∅ Young people want ∅ change.
People in the sense of a collection of persons never takes a definite or indefinite article. “The people” and “the English people” are different meanings of the word people: a social or national grouping.
Change in this sentence takes the null article because the sentence is about the general concept. Young people want change in general, not a specific change.
It's right that there aren't so many ways of spending ∅ daily life in the suburbs.
There is no article before “daily life” for the same reason as “change” above.
“The suburbs” is rather an exception to the general rules of articles. It's a set phrase, meaning peripheral areas of cities in general. I can't see a logic to it, but the usage is undisputed.