Versilia

If Rome2Rio.com can be trusted (I haven't verified this on the TrenItalia and bus websites), you can take a train to Viareggio and a bus from Piazza Dante, near the RR station.

Probably not beach weather much anymore, but there are trains and buses from Lucca to Viareggio or all the way up to the Forte dei Marmi.
trains:
http://www.trenitalia.com
Buses (E1 or E2):
http://www.lucca.cttnord.it/Linee_e_Orari/Linee_Extraurbane/L/573

Agree with Roberto, you can go to the beach, but you won't have much of a beach experience, the weather is not very beach-like and you probably won't ever be able to go into the water.

I was in Viareggio one week ago, the last day of September, very pleasant weather to have a stroll along the liberty-styled seaside passeggiata, but definitely not beach time.

Thanks everyone. I simply just want to walk along the edge of the sea. I live on a small Island here in North Carolina and just like to compare beaches whenever I am traveling. Do you know if any of the shops or cafes will be open this time of year?
Sue

Viareggio will be fully open except for the beach rentals. It's a wonderful place - we stop by every visit. It was the seaside town available to Florence when train travel began, and this lead to rapid development in the 1920's which attracted the upper classes (Puccini had a house here).

In the center, there's a long pier that extends into the sea and makes for good vistas. Alongside is a canal along which several fry boats dock toward noon and make for a nice seafood lunch, and there's usually several boats offering an impromptu fish market. Across from the canal are extensive docks where you can inspect any kind of boat, including gigantic new ones awaiting the next billionaire.

Parallel to the sea is the famous Versilia promenade which extends something like 20 miles. In town, it's lined on the sea side with clothing shops, restaurants, bars, etc., and behind them is the beach. On the far side are numerous large hotels from the 1920's or so. From late morning, the street is full of strolling people of every type and is constantly entertaining. The buildings are often unique and reflect the unique 'Liberty Style' which is the Italian evolution of Art Nouveau.

Intown there's a semi-open air market with food, seafood, and specialty stores that makes for good snooping. There are also famous pinewood parks to the north and south of the center that are full of paths, amusements, and restaurants.

Thanks Mike, This is exactly the information I was looking for! We will be renting a car and take a day trip there for sure!! I appreciate your insight.
Sue

If you have a car consider also visiting Forte dei Marmi, a smaller but more upscale version of Viareggio. In summer the town is full of Italian VIPs (including tenor Andrea Bocelli who has a home there). Occasionally it's also visited by international stars.
Nearby, while in Lucca, you could also go to the Carrara quarries
http://www.cavedimarmocarrara.com/en/tourist-information.html
or ride the Lucca-Aulla scenic train
http://www.verdeazzurronotizie.it/wp-content/uploads/2015/04/ponte-in-garfagnana1-1728x800_c.jpg

If you have a car, you may spend an hour visiting the Puccini villa at Torre del Lago, full of Puccini memorabilia. The maestro is buried in a small chapel within the house, built after his death. When he lived there, the place was absolutely rural but he liked it so; half of the local population boasts that their grannies were at the time having adventures with the fascinating maestro.
He moved near the Viareggio pinewood area in the last years of his life. The reason I went to Viareggio last week was to visit the later villa that is in very bad state and not open to public, but I was able to book a visit in a very rare open weekend.