Here is a selection of tried and trusted longer activities that are much than just lesson-fillers and warmers.
Activities for all ages and levels including role-plays, debates, grammar focus and some simply to get students using their imaginations.
A child's imagination is a beautiful thing
If you really enjoy your work and genuinely like your students then you'll already have the skill set needed to be able to determine what kids will enjoy while they are learning. My rule of thumb is... if I don't like it, my students won't either.