The road from Solano to Manila runs through the centre of Luzon so unless they're interested in staying at a mountain resort, one on the coast would require quite a bit of travelling.
Other options would be south of Manila or the Camaya Coast in Bataan. Nasugbu in Batangas Province is probably the easiest to get to in the south and is around 40 miles from the capital.

Puerto Galera is a nice place to stay if you take Sabang out of the equation but it's a three hour journey including a one hour boat ride.

Other than that, Tagaytay, famous for its volcano and lake and being home to the largest jigsaw puzzle in the world - but it's not on the coast.