Learn Hardcore Japanese: mukou no kaizyou ha ookiino ni, yoyaku no aki ga sukunai. - The venue over there is big, yet there are few openings.

向こう (むこう) means “over there,” “the other side,” or “the other place.” It often contrasts with “this side/our side.”
あっち is casual “that way/over there,” while あちら is the more polite version. 向こう is neutral and often used for “the other” of two locations.
向こうの会場 = “the venue over there / the other venue (as opposed to this one).”

What exactly does 会場 mean? How is it different from 場所 or 会館?

会場 (かいじょう) = the venue/site where an event is held (hall, room, or area set up for an event).
場所 = “place/location” in general.
会館 = “hall/building” (a facility), not necessarily the event space itself.
So 向こうの会場 is specifically “the event venue over there.”

Why is は used after 会場 (as in 会場は)? Could I use が instead?

は marks the topic: “As for the venue over there…”
This fits well because the sentence comments on that venue’s situation (despite being big, few openings).
You could use が (向こうの会場が大きいのに…) to highlight or contrastively identify the subject as “the venue over there.” However, with のに, using は to set the topic is more common and reads more naturally here.

What is the の in 大きいのに doing? Is it the nominalizer?

Here, のに is a single conjunction meaning “even though/although.” The の is not a standalone nominalizer in this case.
You cannot say 大きいに; のに must stay together.
Think of のに as one unit: “[clause] + のに = even though [clause].”

What does のに mean, and what nuance does it add compared to けど/が?

のに = “even though/though/despite,” expressing a result that is contrary to expectation. It often carries a nuance of surprise, frustration, or dissatisfaction from the speaker.
けど or が are more neutral “but/however” and don’t necessarily imply the speaker’s frustration.
In this sentence, 大きいのに suggests “You’d expect a big venue to have openings, but surprisingly/unfortunately it doesn’t.”

When do I use なのに instead of のに?

Pattern:
- Verb (plain) + のに → 行くのに, 雨が降るのに
- i-adjective + のに → 大きいのに, 寒いのに
- Noun/na-adjective + なのに → 学生なのに, 静か(だ)なのに
So with nouns and na-adjectives, use なのに; with verbs and i-adjectives, use のに.

Is this のに the same as the “for” のに in sentences like 勉強するのにパソコンが必要だ?

No—there are two uses that look the same:
- Concessive のに = “even though” (your sentence).
- Purpose/usage のに = “for / for the purpose of” (e.g., 勉強するのに必要だ = “necessary for studying”).
Quick tests:
- If you can replace it with けど (“but”), it’s concessive.
- If you can replace it with ために (“for the purpose of”), it’s the “for” usage.

What does 予約の空き literally mean, and why use の there?

予約 (よやく) = reservation; 空き (あき) = openings/available slots.
予約の空き literally “the openings of reservations” → “reservation openings/availability.”
の links two nouns in a possessive/attributive way.
You’ll also see the pattern Nに空きがある (“there are openings in N”), e.g., 予約に空きがある. Here we’re using the noun phrase “reservation openings” as the subject.

Could I say 予約が少ない instead of 予約の空きが少ない?

Be careful: 予約が少ない means “there are few reservations” (i.e., not many people have booked), which implies lots of availability—the opposite of the original sentence.
予約の空きが少ない means “there are few openings” (availability is low).

Why is が used after 空き (空きが少ない)?

少ない is an i-adjective describing the quantity of the subject. The subject (空き) is typically marked by が when you state or measure a property.
空きは少ない is also possible; it topicalizes/contrasts “openings” (“as for openings, they are few”). が sounds more neutral/informational here.

What’s the difference between 少ない and 少し?

少ない (adjective) = “few/in short supply.” It describes a noun: 空きが少ない (“openings are few”).
少し (adverb) = “a little/a bit.” It modifies verbs/adjectives: 少し空いている (“it’s open a little”), 予約の空きが少しある (“there are a few openings”).
You can’t say 空きが少しない; that’s ungrammatical.

How do I make this sentence polite? Can I put です with のに?

Keep the first clause plain before のに, and make the sentence-ending predicate polite:
- 向こうの会場は大きいのに、予約の空きが少ないです。
You don’t attach です right after のに. For a more formal feel, you can also use:
- 向こうの会場は大きいのにもかかわらず、予約の空きが少ないです。

Are the spaces in the original sentence normal in Japanese?

No. Standard Japanese writing does not use spaces between words. They were likely added to help learners parse the sentence.
A natural written form would be: 向こうの会場は大きいのに、予約の空きが少ない。

Any alternative natural ways to express the same idea?