[X] There are moments where your choice is all that matters. You have won Stannis' victories and you are betrothed to his only daughter. The men will support you. Do not be afraid to leap. Take the throne.
[X] Edric Dayne will make a fine Lord of Dorne with the Martells broken. Pressing his (nonexistent) claim would shift power away from the Rhoynar. Perhaps a marriage to Arya could work as well, for he seems a decent enough lad.
[X] Sleep with the hot blonde chick and Arianne Martell. Whichever one bears our child first will have their kid inherit the throne of Sunspear and the Lord Paramountship of Dorne. The other will of course be kept, with her mother, as wards/captives of the Crown (to be used should the other family start shit up again! Always nice to have a spare dynasty with claims under your thumb to keep things under control!)
[X] Lady Yronwood has been recovered by Lord Tarly. With her betrothal canceled, she is heir to your promise to her father. She may not know that, but she would make a fine puppet ruler and could be wed to a man of your choosing to secure her and her children's loyalty.
[X] The Prince of Dorne is an old and sickly man. Write to his daughter and ask for her compliance and surrender. With her wed to a man of your choice and any other claimants removed, Dorne could be secured. Or perhaps a different sort of arrangement could be made if you met her face to face.
[X] Lady Yronwood has been recovered by Lord Tarly. With her betrothal canceled, she is heir to your promise to her father. She may not know that, but she would make a fine puppet ruler and could be wed to a man of your choosing to secure her children's loyalty.
[x] Prince Doran can have one chance. Surrender unconditionally and he and his line will be allowed to return to the realm (with hostages) and his brother's bones will be returned. You extended an olive branch with Ser Gregor's head and were met with silence.