I've mentioned previously, having traveled extensively in Mexico, Central and South America that many Europeans (and Brits, of course) over look the
west coast of Mexico for just the things you reference. Especially away from the usual touristy areas of Mazatlan, Vallarta and Acapulco. One of the most overlooked is Manzanillo, and of course Ixtapa.
Manzanillo is quite tropical, and since it's on the same latitude as Hawaii, the Pacific is blue, the sands are white and Mexico City is close enough to visit for a day. Plus the old colonial towns of Colima and Comala shouldn't be missed. Here's a site that will give extensive information:
http://www.tripadvisor.com/Attractions-g150791 -Activities-Manzanillo_Pacific_Coast.html
Enjoy!