Yeah, sounds like you're stuck on #5. As for #7, that was right about when Boy hit his fire trucks phase. While I'm often a fan of non-major brands, on the fire truck front I never found anything to equal the Rescue Heroes line by Fischer-Price. Excellent quality and were still like-new when we handed them off to a younger child. Good quality wooden blocks were another big favorite. Unfortunately 4 is sort of too old for Duplo but not quite old enough for Lego for lots of kids. Boy also really dug the whole dress up thing at that age. He had a doctor kit from FAO Schwartz and a wide assortment of hats and gloves and costumey bits.

If you're the book-giving relative (which I am), the Pigeon books by Mo Willems are to die for. Don't Let the Pigeon Drive the Bus! Also the "Click Clack Moo" series by Betsey Lewin and Doreen Cronin are hysterical, age-appropriate and are still favorites in our house.