Hello We will be in Venice last of August and we are thinking about taking the train to Trieste and walking the carrusos for a full day before heading west to Monterosso. Any input on this ...is it worth making the trip?

Did a day trip Venice to Trieste and walked all around - a lovely town with neat old sections of wooden buildings - but what are 'carrusos' - Google tells nothing - what did I miss? Anyway, Trieste IMO is definitely worth it in any case - really underrated IMO. Now about getting there - 2 hours on direct regional trains - tickets for regional trains best bought at station day of train - can buy tickets online but then you have a narrow window of validity whilst bought at station would be valid all day coming and returning - so no need to pre-book - same dirt-cheap price at station - just remember to validate own tickets by sticking them in cancelling machines on platforms - each way (buy return ticket in Venice) - trains leave Venice Santa Lucia hourly. For lots on Italian trains and things like first v 2nd class (these regional trains have both classes and 1st is also cheap and more leisurely - more empty seats usually and roomier) check Acquista il biglietto con le nostre offerte - Trenitalia - Italian State Railways; www.seat61.com; BETS-European Rail Experts and www.ricksteves.com.

So SVP what are carrusos? Pardon my ignorance. But in any case I found Trieste ("tree-est-uh I heard) to be really neat in any case. Very Austrian flare evidenced in Trieste train station caffe with Austrian coffees!

I confess I don't know what "carrusos" are either, but we were just in Venice, Trieste, and Verona during the middle of June. It was breezy in Trieste and not a single selfie stick in sight which is a welcome change from Venice which we loved. It's an easy direct trip on the train.

Wow - what could carrusos possibly mean - to walk -maybe some historic streets where Caruso lived (if did here) - hopefully OP will enlighten us.

Perhaps the OP means the Carso
https://www.roughguides.com/destinations/europe/italy/friuli-venezia-giulia/carso/

Thanks ellenem, I wouldn't have thought about.
Description of the hiking trails nel Carso around Trieste:
Trieste - Itinerari
I SENTIERI DELLA VAL ROSANDRA

seems way too much for a day trip?

Funny OP has not chimed in about Carrusos or Carusos and which one they want to walk.