In this case, Mrs. Peel, I believe "discussions" is in the plural, and therefore "these" is appropriate.
Punctuation might be a fraction off, however, and I think the sentence might be read thus:
"I so enjoy discussions like these", she said, wielding a bloody axe in her hand.
Thank you both. So far it looks as though we have one vote for this and one vote for these. I'm not clearer in finding the proper solution.