train Venice to Rome May 1?

There is no point stressing over a strike - it is very unlikely you will be affected.

Regarding the night train, you need to catch a 21:12 from Venezia SL, then connect to the night train at 23.36 in Verona. It arrives in Roma Termini at 06.00. This shows on Trenitalia for the 1st of May (make sure you use the italian spelling i have).

Having said that, I would say you are much better off getting a frecciaargento day service, taking just under 4hrs. You proably won't get a great sleep on the night train with all the stops etc.

Regarding your last question, can you please clarify? If you only intend to have two nights in Venice and 3 in Orvieto then I think you have it the wrong way round and should have the extra night in Venice. But maybe I misunderstand.

Thank you for the clarification on the night train. I agree that a day train makes more sense.
As for Orvieto or Venice , we must choose only one for the 3 days and nights we have open.
My main concern is the May 1 holiday and possibility of strike - especially since it is also a Friday.
Do you or others reading this know what happens if you have made a reservation and there is a strike. Would we just need to buy new tickets at the same day price for whenever available?
Any suggestions welcome. We had been cautioned here to buy the tickets well ahead of time as it is a popular run.

http://www.trenitalia.com/cms-file/allegati/trenitalia/servizi_per/tabellaA_treni_garantiti.pdf

Go to the PDF link above. it will show what you what services are guaranteed to run in the event of strike action. If you are really concerned about the possibility of a strike book one of the services from Venezia SL to Roma that are shown on the list.

And if you have not been to Venice before, there is no contest, definitely do Venice over Orvieto. In fact even if you have been to Venice before....

Finally, in addition to the link I posted above. Trenitalia will post information about any strikes a couple of days beforehand.

Not only is a strike on a a holiday unlikely, the freccia trains run during strikes. Are you planning to take the Frecciargento? Spend your 3 nights in Venice.

I will say that local buses stopped entirely in Rome on May 1 last year, from about 13:30-16:30. Apparently the bus drivers get to celebrate Labor Day in this way.

The probability of a train strike on May 1st is very very low. Till a few years ago it was a virtual impossibility. Now some employers are trying to force work on Labor day and unions may consider striking against them, but this is not the case of the railway administration, whose times are set well in advance.

Day of the week makes no difference in terms of scheduled travel; some lines may have fewer trains on Sundays and holidays, but the published schedules won't change except for a strike or other unforeseen calamity.

A strike in Italy is announced well in advance, lasts for hours rather than days or weeks, and when that has happened to me (twice in 40 years), my reservation was changed to the next available train at no charge (ticket was reissued).

Thank you to all who replied. It is wonderful to have a place to ask questions. There seem to be a million things to decide as we plan our first trip to Europe. We have traveled extensively in central america and mexico but this seems to demand more planning. Is it just because of the expense? Anyway, I hope to relax and enjoy. Thanks again. Travel well.