Over the years, we've had all those arrangements (except the single parent part; DH has never been away for more than a few nights), at different times, and I think maybe a few others as well. I remember one phase when the twins were about six months old when DD1 would fall asleep in her own bed in her own room, and DH went to sleep downstairs with DD2, and I went to sleep upstairs in my room with DS, but then at about 2 am DD2 would wake up, and I would go nurse her downstairs, while DH crawled in with DD1, and then once I had DD2 asleep again, I'd put her in a crib in the room with DH and DD2, and go back to DS again.
Yeah. So I picked other.
Our present arrangement is all three kids (DD1 is 5, and DD2 and DS will be 3 in a few weeks) sleeping in one bedroom together, and me and DH in the adjacent room, but we have a trundle bed under ours that is frequently occupied by one child or another. Not DD1 so much, but one or the other of the twins, usually for only part of the night, maybe once or twice a week. DS is going through a phase of having a lot of nighttime fears, so he's been sleeping with us fairly often the last few weeks.
We are believers in doing whatever works best to get everybody a good night's sleep, no matter how unorthodox the arrangement.