Here is a little tip for you. If you want to have a nice cocktail on the beach and watch the sunset but you have you kids with you, there are not too many places were you can enjoy a relaxed and peaceful time and do it al.
The Bon Aire hotel on St. Pete beach is the place for you. It is a little family operated Hotel right on the beach on the corner of Gulf Blvd and 46 Ave.
They have a great kittle neighborhood beach bar that tourist never find, the beach is very wide in this spot and all the people bring their kids and it is great to see that families can have fun together.