Great suggestions GKCfan, I would also add The Listerdale Mystery, I think this one and the ones you mentioned are great, a while ago 4Extra played a series of Agatha Christie short stories up-dated, I quite liked them I do hope they do more but 4Extra does old R4 stuff so they probably wont :-(
I have not seen The Agatha Christie Hour but I am now intrigued. I'm surprised someone decided to adapt these stories, as they are so different from her other works. I do like some of the adventure ones, however, but feel they could've been expanded into novellas as they usually have complex plotting. I shall try and find this series!
It probably wouldn't pay these days to put them on Television they would probably pad them out and ruin them I would love them to be on TV or radio
I recently got the Complete Marple short stories and mystery set and realised that some of the stand alone Short Stories were in this set, glad to know that they are up to a reasonably good standard. I look forward to watching them!