Simple past or past perfect?

Here is a situation:

I had lunch with Jenny yesterday. Today she called me and said she had a wonderful time with me.

Is it possible to use a past perfect tense here, as ‘she said she had had a wonderful time with me’?

Another situation;
Jenny was supposed to have lunch with Tom and Steve. But when she got to the restaurant, Steve wasn’t there. Tom said Steve went back to his office because there was something came up.
Later Jenny told that to Kerry,
“When I got there, Steve had already gone back to his office.”

Is it possible to use a simple past tense here? Also, is it supposed to be ‘Tome said Steve had gone back’ or ‘Tom said Steve has gone back to’?

Thanks in advance.

Thanks Pieanne.
Doesn’t ‘I had had a good time’ imply that their good time was completely over, that they wouldn’t have a good tome again?

There is no logic behind this to back up my concept, but I just feel that way.

I'd use past perfect in all three cases myself. I use past perfect for one of the two past events if two simple pasts (together with whatever temporally descriptive words, like 'after', are present) do not make clear which event preceded the other.

'Steve couldn't make it because something came / had come up', actually.

I don't think that past perfect is either preferred or necessary here, as it is clear from the context that 'coming up' preceded 'making it'.

It is more formal to use the past perfect in reported speech, speaking of a previous event. I would suggest you use it in essay-writing, but not worry about it in conversation, as either is acceptable, and 'came' is probably the more common.