One middle-aged couple always brings wine, rugelach, and toys for the kids. The first time they came, the husband explained that the toys are meant to keep the kids busy so that the adults could talk.
One guy who usually comes for one seuda each week doesn’t bring anything for Shabbos, but for Yom Tov he brings an expensive bottle of vodka and a cake.
When girls come, they usually offer to prepare a dish.
I don’t like when a guest brings flowers on his way to shul, sometimes after I bentched licht. I’d rather he didn’t bring anything.
The nicest gifts we have received from guests were the book, “The 39 Avoth Melocha of Shabbos” by Rabbi Boruch Chait, and a Brochos Lotto game for the kids.