Bedtime reader question

My daughters are 6 and 3. They share a bedroom, and have separate beds. Lately it has become such a battle to get them to go to sleep. They talk and goof off, come in and out of their room, and just will not go to sleep. Last night I started putting them to bed around 7. My oldest (who has to get up early for school) was still awake come 9-9:30. Some nights are even later. I don't know how to get them to go to sleep. Should I put one to bed first and let the other stay up a little later? Do I forfeit the playroom, and give them each their own room? Do I figure out a REWARD system to get them to go to sleep? I am at a loss. They used to be fine and now it is madness. I do stick to a routine before bed, but it isn't helping. Any advice?