Learn Hardcore Finnish: Setä ehdotti, että menemme taksilla lentokentälle. - My uncle suggested that we go by taxi to the airport.

Standard/neutral written Finnish prefers the conditional for suggestions: Setä ehdotti, että menisimme… = “Uncle suggested that we (should) go…”
Setä ehdotti, että menemme… is common in speech. It can sound like reporting a plan that’s being put forward as if it were already decided (“he proposed that we are going by taxi”), or just be casual/colloquial phrasing of a suggestion.
Very common in speech is the impersonal conditional: Setä ehdotti, että mentäisiin taksilla… = “Uncle suggested that we go (let’s go) by taxi.”

If you want the safest, textbook-like version of a suggestion, use the conditional: että menisimme (or the impersonal conditional että mentäisiin).

Why is there a comma before että?

Että introduces a subordinate content clause (a “that”-clause), and Finnish puts a comma before such clauses in standard writing. So you write: … ehdotti, että …

What exactly does setä mean? How is it different from eno?

Setä = paternal uncle (your father’s brother).
Eno = maternal uncle (your mother’s brother).
Täti = aunt (on either side). Also, setä is sometimes used as a polite form of address for an older man, especially when speaking to children.

How do I say “my uncle suggested …”? Is plain Setä enough?

Plain setä is indefinite (“an uncle”). To say “my uncle”:

Standard: Setäni ehdotti… or Minun setäni ehdotti…
Colloquial: Mun setä ehdotti… (dropping the possessive suffix is normal in speech).

Why is it taksilla? What does the ending -lla do?

-lla/-llä (adessive) often expresses “by/with (as a means)”. So taksilla = “by taxi.” Common transport examples: junalla (by train), bussilla (by bus), autolla (by car), pyörällä (by bike).

Alternative phrasing: ottaa taksi(n) (“take a taxi”) or ottaa taksin lentokentälle. Mennä taksilla emphasizes the means; ottaa taksin emphasizes the act of taking/booking one.

Why is it lentokentälle and not lentokenttään?

Finnish has two series of “to/at/from” cases. Some places are conceptualized as surfaces/areas and use the -lle/-lla/-lta series (allative/adessive/ablative). Lentokenttä (“air field/airport”) belongs to this group:

to the airport: lentokentälle
at the airport: lentokentällä
from the airport: lentokentältä

So you don’t say lentokenttään. Many open areas and stations behave the same way (e.g., torille, asemalle).

Can I swap the order to … että menemme lentokentälle taksilla?

Yes. Both … taksilla lentokentälle and … lentokentälle taksilla are fine. Word order can highlight what’s new/important:

Ending with taksilla can contrast the means (not by bus, but by taxi).
Ending with lentokentälle can highlight the destination (not to the hotel, but to the airport).

Does menemme mean future here? Finnish has no future tense, right?

Correct. Finnish uses the present for future when context makes it clear:

… että menemme … = “that we (will) go …” Time is inferred from the situation (e.g., a plan for later).

Could I use mennään or mentäisiin instead of menemme?

että mentäisiin (impersonal conditional) is very common and natural for proposals: “that we (should) go.”
että mennään (impersonal present) is widely used in speech but is colloquial; in careful writing, prefer että mentäisiin or että menisimme.

Can I leave out että and say something else with ehdottaa?

Yes, two common options:

Use a noun phrase object: Setä ehdotti taksia (lentokentälle). = “Uncle suggested a taxi (to the airport).”
Keep the että-clause (most explicit): … ehdotti, että menisimme/mentäisiin… A nominalization is possible but bookish: Setä ehdotti menemistä taksilla… The pattern ehdottaa + tekemään is not idiomatic; use kehotti/pyysi/käski menemään with verbs of urging, not ehdottaa.

What’s the nuance between mennä and lähteä here?

mennä focuses on going to a destination: mennä lentokentälle.
lähteä focuses on the act of setting off: lähteä lentokentälle. Both are fine; choose depending on whether you stress the destination or the departure.

Any pronunciation tips for this sentence?

Stress is always on the first syllable of each word: SE-tä EHD-ot-ti, ET-tä ME-nem-me TAK-sil-la LEN-to-KEN-täl-le.
Double consonants are long: että has a long tt; keep it clearly long.
ä is a front vowel (like the a in “cat,” but pure and a bit tenser).
Vowels are pure and length matters: menemme has three short e’s; don’t reduce them.

Is taksi spelled with x in Finnish?

No. Finnish uses taksi (k-s), not “taxi.” You’ll see the English spelling in English contexts, but in Finnish text it’s taksi.

Could I say lentoasema instead of lentokenttä?

Yes. Lentoasema means “airport” as well, and it also uses the -lle/-lla/-lta series:

lentoasemalle, lentoasemalla, lentoasemalta. Pick the word your context prefers; both are common, with lentoasema being a bit more formal/official.