Doll strollers and shopping carts are a huge hit with everyone from 1-4...and of course a few dolls to go with them (clothing need not be abundant or fancy because at that age they often just strip them naked and leave the clothing on the side...hahaha). Building blocks of some type (mega blocks or wooden blocks etc) are great because they can be used in so many ways. Dress-ups are great as you mentioned...you can often find things around your own house to throw into that box or pick up things at Thrift stores. Playdough tools have been a good investment for me because the kids love to play with playdough for hours on end at times and they absolutely love the little spaghetti maker thingies for pushing playdough through as well as the little rollers and cutters. Otherwise, I find I spend the most on arts and craft supplies...for example a big bin of pom poms which the kids use for sorting, picking up with tweezers, making patters, or putting into and out of wipes boxes (never throw wipes boxes away...they are an awesome toy for all ages!).