There are lots of small drinking establishments dotted along the main walkways in Placencia. Most of them are pretty good and relatively cheap.
There are sometimes a few problems though:
Some of the bars run a tab based service which can be a problem. Keep track of what you have been drinking.
Also we had a local (called John Wayne) sit down with us and order drinks, only to try and make us foot the bill. So be careful that people don't try and take advantage.
Dress Code: General easy going, no general dress code in Placencia's bars
We arrived in Placencia on a Sunday which lucky for us was the night the Barefoot Bar and grill has live music. The Barefoot is located mid way on the boardwalk, there is a large empty sand lot next to them. Our hotel was right next to it so we headed over and where plesantly suprised with some good live music 6-10pm. The music was good and it brought out a lot of tourist as well as a lot of the locals. There is a huge outdoor dance floor that sits between the outside bar, the stage for the band and Tipsy Tuna's sports bar. We had a lot of fun, the drinks are good and the food is WONDERFUL.
During the day it's a good place to get sun, they clean up the beach, rake it and have lounge chairs for people to use.
Dress Code: No shirt, no shoes - no problem. Casual but as day turns into night a number of people change to beach casual.