Interesting question & more interesting replies!
Well, there should have been one more option, the main person from that family - HUSBAND!
Since you omitted that option, I think it'll be either my sil or my bil. Both are quite ok to be with. My sil is quite a nice person. My bil too; he is much younger than me & would miss his parents (danger!). Also, my sil would be better company. So sil is my choice.
Fil and mil are the last options - if you promise there will be special internet access just for me (to visit Indusladies if need be

). And no phone on the island, may be I can live with them. Otherwise, they will call their son and start complaining about me and creating problems

Cheers,
Sandhya