rainen ha kazoku to issyo ni kyouto he kankou ni iku tumori desu.

は marks 来年 as the topic: as for next year or next year, ...

Also, 来年 usually does not take に, because it is a relative time word like today, tomorrow, or next week. So:

• 来年行きます = I’ll go next year
• 来年は行きます = As for next year, I’ll go / Next year, I will go

Here, は gives 来年 a topic or slight contrast feeling.

Japanese often leaves out the subject when it is obvious from context.

So even though English needs I, Japanese does not have to say 私は here. The sentence naturally means something like:

• (I) intend to go sightseeing in Kyoto with my family next year.

If needed, you could say 私は, but it is often unnecessary.

家族と一緒に means together with my family.

The parts work like this:

• 家族 = family
• と = with
• 一緒に = together

Using both gives a natural sense of going together with someone.

You may also see just:

• 家族と京都へ行く = go to Kyoto with my family

But 家族と一緒に emphasizes that you will be together.

In 一緒に, the に turns 一緒 into an adverbial expression, so it functions like together in English.

• 一緒 = together / the same
• 一緒に = together, jointly

So:

• 家族と一緒に行く = go together with my family

This に is part of a very common pattern.

Both へ and に can mark a destination with verbs like 行く.

• 京都へ行く
• 京都に行く

Both mean go to Kyoto.

The difference is small:

• へ slightly emphasizes direction toward
• に slightly emphasizes the destination itself

In many everyday sentences, they are almost interchangeable.

This に is different from the destination marker.

In 観光に行く, the pattern is:

• noun + に + 行く

This means go for the purpose of ...

So:

• 観光に行く = go sightseeing
• literally: go for sightseeing

Other examples:

• 買い物に行く = go shopping
• 食べに行く = go to eat

So the sentence has:

• 京都へ = destination
• 観光に = purpose

つもりです attaches to the dictionary form of a verb.

So the correct pattern is:

• verb dictionary form + つもりです

Examples:

• 行くつもりです = intend to go
• 食べるつもりです = intend to eat
• 勉強するつもりです = intend to study

So 行きますつもりです is incorrect.

つもりです means intend to or plan to.

It expresses the speaker’s intention. In this sentence:

• 行くつもりです = I intend to go / I’m planning to go

It is a little more deliberate than just saying 行きます.

Compare:

• 京都へ行きます = I will go to Kyoto
• 京都へ行くつもりです = I intend / plan to go to Kyoto

つもり is a noun-like word, so it is followed by です in polite speech.

That is why you get:

• 行くつもりです = polite
• 行くつもりだ = plain

So the sentence is polite because it ends with です.

A good breakdown is:

• 来年は = next year / as for next year
• 家族と一緒に = together with my family
• 京都へ = to Kyoto
• 観光に = for sightseeing
• 行くつもりです = intend to go

So the overall structure is:

[time/topic] + [companion] + [destination] + [purpose] + [main verb + intention]

This word order is very natural in Japanese because details usually come before the main verb.

Yes, but it would change the structure a little.

• 京都へ観光に行くつもりです = I intend to go to Kyoto for sightseeing
• 京都で観光するつもりです = I intend to do sightseeing in Kyoto

The first expression focuses on going there for that purpose.
The second focuses more directly on doing sightseeing there.

Both are natural, but the original sentence is a very common way to say it.

It behaves a bit like a noun, but in practice learners often remember these common patterns:

• 一緒に = together
• 一緒だ = be together / be the same
• 一緒の
  • noun = same / together, in some contexts

In this sentence, you only need to know that 一緒に is a set phrase meaning together.

A natural reading is:

らいねん は かぞく と いっしょ に きょうと へ かんこう に いく つもり です。

A few pronunciation notes:

• 一緒 is read いっしょ
• 京都 is きょうと
• 観光 is かんこう
• 行く is いく

So the full reading is:

らいねんは かぞくと いっしょに きょうとへ かんこうに いく つもりです。