Maybe i'm the only lazy tourist here but we have a 4yo daughter, so we can't do much excursions and we always take a kids-friendly hotel where she can play at the swimming pool slides.
Last year I sat at the swimming pool and could make some nice candids.
Later on I walked in the pool with my 16-35 II and recorded some wide angle movies, nice memories for later of her first holiday abroad.
Anyone uses also a 70-200 2.8L to take candids of their kids on holiday, or do you find a 70-200L too exagerated at the pool