day trips from Rome by train

Hello everybody!

What day trips can you suggest for people who travel by bus or train?

I already know:

Santa Severa
Santa Marinella
Civitanova
Bracciano
Formia
Anzio
Nettuno
Viterbo
Ostia
Sperlonga
Ladispoli
Frascati

All of these places are very easy to reach by train. Only in Sperlonga, one has to take the bus or taxi from the train station.

Any other suggestions?

Anybody up for a trip?

I have time on Wednesday or Thursday

Lydia