I lived 6 months in Mazatlán, landed 10 days ago in PDC. Night and day. In Mazatlán is the expat community builded around retired couples in their 70's. Almost no one in the city speaks english. Although the city nice and has beautifull beaches. PDC is tropical paradise, better restaurants and services. Lots of poker and non-poker expats and almost everyone speaks english. If you plan to play cash games, come to Playa since it seems everyone here plays mtt's
The prices - 1000$+ studio/1bed in central, 10-20$ meals in restaurants.