Dapoli Area (Karde/Murud Beaches) is a good option about 200 km from Pune. Takes about 4-5 hours by car. Routes 1. Via Mulshi-Tamhini Ghat 2. Via Bhor - Varandha Ghat

Note - you won't find top luxury hotels (like Goa) there, but basic decent accomodation.

Alibag Area. Takes about 3-4 hours by car.

I often travel to Konkan beaches and have stayed in resorts to home stay options. Please note that konkan is still not (Thank GOD!) as commercialized as Goa. Hence stay and food options cannot be compared with Goa.

Nagoan is one of the closet beaches near Pune (take express way and Khopoli exit). The road condition is excellent and you can reach the place in 3-4 hours. Two resorts in Nagoan that are worth a try: http://www.karpewadi.com/ http://www.shintrewadi.com/

Most of the MTDC resorts on Konkan coast are value for money.

Diveagar is a nice option. You can visit Shreevardhan and Harihareshwar too along with it as they are nearby.

+1 for Dapoli. Other good option is Tarkarli near Malwan. But it is not exactly close. It takes around 7 hours to reach there. Tarkarli MTDC Resort is excellent. Since it would summer, AC rooms are perhaps preferable. Avoid Houseboat.

There is no train.

Goa is best n laid back in this season..Except for the free sauna in daytime... Vagator is a Nice n w/o much hustle bustle...U could rent guest houses just minutes walk from the beach..Other better places would be Colva[crowded thou],arambhol.Palolem is another laid back place..Being in Goa keeps u accupied for 3-4 days Heartily.. Have traveled By the Nizamudin Goa express,nothing Spcl abt it coz it travels night n gets you in Vasco early morning

Else Tarkarli-Devbagh[near Malvan] is a nice place for family outing with much things to do..Backwaters,snorkelling,Dolphin rides,much more [Could find more about Tarkali on my travelogue on my blog @ rollingstonerishi.wordpress.com]

Other options can be Nagaon, Kashid beach and Murud Janjira. They are few kms away from each other.

You can reach the Konkan beaches in Raigad dist. within 3:30-4:00 hours. We drove to Diveagar last week and had the whole stretch of wonderful beach just for ourselves. Kashid, Murud-Janjira to the north of it and Sreewardhan, Harihareshwar to the south of it are also good. There are many homestay opportunities in most of these locations.

Though many suggest the Mulshi-Tamhini ghats route as the distance is less, it can be stressful due to steep curves, road conditions etc. Best way is through Expressway and then take Khopoli exit to Pali, and then the Mumbai-Goa highway (NH-17).

You can also enjoy homemade seafood at these locations!

April is gonna be hot. Too hot for kids maybe.

We've been going to Tarkarli for the last couple of years. Beautiful talcum-powder-soft white sand, close to Malvan (so you can grab some of that famous Malvani first-hand), you can do snorkeling, Sinhagad and dolphin trips, backwaters, sandbar... Awesome place. The only issue is that the 8-hour drive is a little stressful with kids. We staggered it by spending the night at Amboli. I recommend "Gajanan" as a staying option - inexpensive, clean, good home-style cooking (Ph: 02365251401)

Warning: Tarkarli is being overrun with tourists and water bottles. It was pristine in 2009, but pretty littered in 2010.

Last week (end March 2011) we went to Agonda Beach in South Goa. Also great beach, white sand, clear water. Took Konkan railway trains (Netravathi and something else) from Panvel to and from Canacona. Beware that most trains stop only a couple of mins at Canacona, boarding is a challenge w/ kids.

Awesome place, no crowd at all (avoid Palolem! Like Chowpatty in Bombay but more crowded and expensive). But it's getting pretty hot there too. I recommend staying at the north end of the beach - it's much broader. Agonda White Sand, Chattai Huts, Seaview are on the north side. My only crib is that food in Agonda tends to be restauranty, unlike Konkan.

Always scout out a place on wikimapia to see how far away it is from the beach, how wide the beach is etc. Always served me well.