After the Reed and Stoddard stories, April's F&SF takes a turn for the slipstream. "The Nocturnal Adventure of Dr. O and Mr. D." by Tim Sullivan, involves two characters wandering around a foggy, suburban landscape. They visit another character. If you'll pardon the spoiler, it turns out they're all dead. They continue wandering. I read a similar story back in March ("The Second Descent" by Richard Paul Russo, and my opinion stands. I'm biased against these sorts of stories, so they have to work harder/be better to overcome my resistance. This one doesn't do it. I finished it, but that's about all I can say for it. I feel bad - stories using this trope are obviously well-received, and I'm sure the authors are saying interesting things about the human condition. Unfortunately the message doesn't get to me through the vagueness of it all.
A better slipstream story is Kate Wilhelm's "The Fountain of Neptune." A woman discovers that she is dying and has only months to live. She pulls up stakes and moves to Rome to enjoy her final days in beautiful settings, not surrounded by sadness. Her illness is a brain tumor, and when she begins to see changes in the eponymous fountain, she thinks she's beginning to succumb. A handsome man strikes up a conversation with her, and she begins to think that maybe something more fantastic is going on. In the end she embraces the mystery of what the man and the fountain represent. She probably also embraces her own death, but it feels like a life-affirming choice. The only minor quibble I have with the story is that it completely ignores the logistical difficulties of moving to Rome, and never mentions where she is getting the money for this sort of thing. Totally over-literal thinking about a story this nice, I know, but that omission stood out for me. Personal quirk, nothing to really detract from the story for most people: just assume she's putting it all on credit cards and keep reading.
Going back to classic sf, the final story is "The 400-Million-Year Itch" by Steven Utley. It's set in a universe he's written in before, where we've established a physical link to another universe, one where the Earth is barely past the primordial-soup phase. The main character, Amy, is an assistant to Dr. Cutsinger, the man who established the link. He's a great man, in much demand, but a complete jerk to work for. Everything revolves around him, and Amy is beginning to realize that she may never escape from his orbit to have a real career in physics for herself. For the first time, Dr. Cutsinger is visiting the other universe, taking her with him, of course. She gets away for awhile to do some serious thinking about her own future. In the meantime, she meets some of the other scientists and celebrities who are visiting the research installation. This is a solid story, a fairly realistic character piece. However, the story suffers from trying to do too much: a lot of time the focus is off Amy and on the dinner table conversations between the various luminaries instead, with an un-named science fiction author getting a lot of page-time. His diatribes, while funny and well-aimed, detract from the core of the story, and sometimes Amy feels like an afterthought in her own story. That may be intentional echoing of her situation with the professor, but to me it felt like a shame.