Learn Hardcore Japanese: dotira no kaizyou ni mo ikenaino ha totemo zannen da. - It's very unfortunate that I can't go to either venue.

どちら usually means “which (of two)” or “either (of two).” In polite speech, it can also mean “which” even among more than two, but with patterns like どちらも / どちらにも, it strongly implies two options.
どっち is the casual version of どちら.
For “which (of many),” you typically use どれ (things) or どの
- noun, and for places you use どこ (or どこの
  - noun).
Here, どちらの会場にも suggests there are two venues being considered.

Why is にも used (に + も)? What does も do in negatives?

も after a case particle adds the meaning “also/even.” With a negative verb, patterns like Xにも…ない mean “not … at any X” or “at neither X.”

どちらの会場にも行けない = “can’t go to either venue (neither one).”
Similar patterns:
- どこにも行けない = “can’t go anywhere.”
- だれにも会えない = “can’t meet anyone.”

Is this a double negative because we have も and ない?

No. This is not a double negative. In Japanese, [indefinite word] + も + negative forms a single negative meaning like “nobody,” “nowhere,” “nothing,” or “neither.” For example, どちらにも行けない simply means “can’t go to either,” not “can go.”

What’s the difference between どちらにも and どちらにでも?

どちらにも with a negative means “neither.” With a positive, it often implies “both are possible.”
- どちらにも行ける = both options are accessible; you can go to either one.
どちらにでも emphasizes “whichever is fine/no preference.”
- どちらにでも行けます = “I can go to whichever (you choose).”

Could I say どちらの会場にも行ける? Does that mean “I can go to both” or “I can go to either”?

どちらの会場にも行ける means both options are feasible — you can go to either one. It doesn’t necessarily mean you will attend both; it means each is within reach/possible.

Why is there a の after 行けない? What does 行けないの do?

That の is a nominalizer: it turns the clause どちらの会場にも行けない (“can’t go to either venue”) into a noun-like phrase so it can be the topic of the sentence with は.
So, 行けないのは… = “As for the fact that (I) can’t go …”

Can I use こと instead of の? Is there a nuance difference?

Yes: どちらの会場にも行けないことはとても残念だ is also correct.

の feels a bit more concrete/immediate and is common in speech.
こと sounds a bit more formal/abstract and is often seen in writing or formal statements.

Why is は used after 行けないの? Could I use が instead (行けないのが…)?

Both are possible:

行けないのはとても残念だ sets “not being able to go” as the topic; it can feel slightly contrastive (“as for the fact that I can’t go, [it’s] a pity”).
行けないのがとても残念だ treats it more as the grammatical subject; it often sounds a bit more neutral/natural as a single remark.
In everyday use, both are fine; choose based on whether you want a topical/contrastive feel (は) or a more neutral statement (が).

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

会場: “venue” — the place where an event is held (the event site as a concept).
場所: generic “place/location.”
会館: a hall/building (often community- or organization-owned).
ホール: a hall (auditorium/concert hall).
In this sentence, 会場 is correct because we’re talking about event venues.

Why 行けない and not 行かれない or 行くことができない?

The potential form of 行く is 行ける (godan verb: change -u to -e + る). Its negative is 行けない: “cannot go.”
行かれない is usually the passive negative (“cannot be gone to,” or “(someone) goes and I’m inconvenienced” in colloquial passive), not the potential of 行く.
行くことができない also means “cannot go,” but it’s longer/more formal. 行けない is the most natural in conversation.
Note: いけない (kana) can also mean “must not/that’s no good.” Here, 行けない (with 行) clearly means “cannot go.”

Can I use へ instead of に (どちらの会場へも行けない)?

Yes, へ is possible: どちらの会場へも行けない.

に tends to mark the destination as a target/arrival point and is more common with venues.
へ emphasizes direction. Both work; に usually sounds more natural here.

How would I make the sentence polite?

Change the final copula to polite and optionally the verb:

どちらの会場にも行けないのは、とても残念です。
Or fully polite: どちらの会場にも行けないのは、とても残念です。 (keeping 行けない is fine inside a subordinate clause even in polite speech)
You could also say: 残念ながら、どちらの会場にも行けません。

Can I drop だ at the end? Is 残念 alone okay?

In this full sentence structure with XはYだ, you normally keep だ/です.

…残念だ。 is standard.
残念！ alone works as an exclamation. But Xは残念。 without だ is more like headline style; in regular speech/writing, include だ/です.

Does どちら always mean there are exactly two venues? What if there are more?

どちら typically implies two. If there are more than two venues, use:

どの会場にも行けない = “can’t go to any of the venues.”
Or どこの会場にも行けない (also natural with places).
That said, polite どちら can sometimes be used loosely, but for clarity with many options, prefer どれ/どの/どこ patterns.

Does this mean “can’t go to either (neither)” or “can’t go to both (at the same time)”?

It means “can’t go to either (neither of them).”

どちらの会場にも行けない = neither is possible.
If you want “can’t go to both (but maybe one is possible),” say something like:
両方の会場には行けないけど、どちらか一方には行ける。

Are there alternative, natural ways to phrase this?

Yes:

どちらの会場にも行けなくて、とても残念です。 (linking reason/result)
残念ながら、どちらの会場にも行けません。 (polite preface with 残念ながら)
どちらの会場にも行けないのが、とても残念です。 (using が)

What about the spaces between words in the given sentence? Are they normal in Japanese?

No. The spaces are for learning/segmentation. In normal Japanese writing you would write it without spaces:

どちらの会場にも行けないのはとても残念だ。

Who is the subject here? Why is there no “I”?

Japanese often omits obvious subjects. Here, context implies “I” (or “we,” etc.). If needed, you can add it:

私はどちらの会場にも行けないのはとても残念だ。
More natural is to keep the subject implicit unless clarification is needed.

What tense/aspect does 行けない express? How would I say it in the past?

行けない is present/future negative potential (“cannot go [now/going forward]”). For past inability:

どちらの会場にも行けなかったのは、とても残念だ（です）。 = “It’s very unfortunate that I couldn’t go to either (in the past).”
Or simply: どちらの会場にも行けませんでした。とても残念です。

What’s the nuance difference between ～ないのは残念だ and ～なくて残念だ?

～ないのは残念だ highlights “the fact that X doesn’t/can’t happen is unfortunate” (more explicit/topic-like).
～なくて残念だ frames it as a cause/reason (“since X doesn’t/can’t happen, it’s disappointing”).
Both are natural; ～なくて can feel a bit more directly causal.