Pretty beach or cove near FCO Rome airport

If you will consider the two-hour mark, Orbetello is great. It is actually on a lagoon, but in the newer part of town you can rent places with water views (great sunsets). The adjacent spit of land, Feniglia, is a lovely sandy beach. The adjoining promontory, Monte Argentario, has some cute villages on the sea and dramatic rocky scenery, but that would add another 30 minutes to your drive. I have only spent time in Orbetello and parts north, but this area is well worth a stop.

Thanks Valadelphia! That area looks like the most beautiful and dramatic part of the coast indeed. I am afraid we would like to be a bit closer or a least a 1/2 hour south as we have to turn in the car and be at Roma termini to meet family at 11 am. We'll have to decide if it's worth getting up at 6 (and having a nervous husband about time).

I completely get it--hopefully one of the regulars will know just the place along the coast in northern Lazio.

On top of Porto Santo Stefano. View and infinity pool to die for. About 1h45min from FCO.
http://www.hvittoria.com

If you can stay two nights, I recommend a day trip to the Giglio island, about 45 min by ferry. You won’t regret it. If you can stay only one night, you can still do it, if you get there early on the day of arrival.

To return the car at FCO and be at Termini by 11, I would leave Porto Santo Stefano before 8am.

Closer than the above, I would probably choose Fregene or Santa Marinella. None will compare to Mt. Argentario, however. Never stayed in either overnight though, only during the day, therefore have no hotels to suggest.

Second Santa Marienlla. It's easy to reach by train, but a longer ride to Termini. Be sure you're aware of Romes ZTLS if driving into Rome city center.