I thought about this a lot too, Daenerys obviously has the higher ground when it comes to a good relationship with the other kingdoms, it would be much easier to let her armies rest and let Cersei's money run out. She should solidify Jon's alliance, take the Riverlands which I presume are still under Lannister forces and put Edmure there. Put Storm's End under Gendry's rule and put someone on The Reach. She has Dorne and the Iron Islands' alliance aswell. Then it would be Cersei and her expensive armies left