I have bought wooden farms and a wooden garage (upgrading his inherited one) for the year my son was 14mths and the year he was 2 and a bit. The farm (Intended for 3 plus) has taken a battering but it has been well loved and I bought happyland farm animals rather than the proper ones. The garage is also played regularly with hot wheels cars now, but we did have toddler wooden ones originally.
In my experience, they play with 'older toys' far sooner and are less interested with toys intended for their own age, so I'd look to age up on gifts.. Another hit was a wooden shop from Asda. It was bought for my elder son, but the younger one loved that and the toy till (without the coins) more.
My DS is roughly the same age, is youngest of 3 and has older DS so we are in the same boat. Also January birthday so two lots of presents to think of. He's getting his older brothers wooden garage wrapped up, neices old plastic shopping trolley, a few new books and a couple of items of clothes. We are going to spend the money in the spring instead and get a slide as the old one broke.
Does he like anything of his big brother’s yet? Our DS2 is 2 and loves his brother’s brio trainset (of which we have loads already). We have, therefore, bought DS2 the start of a Brio road system, so he has something of his own, but which fits with what we have.
We have, however, really struggled with ideas of what to ask others for!
Same problem here: DS2 (2.5) is getting a fisher price car ramp, a toy baby buggy, a few books, and some new Brio/BigJigs stuff to add to our existing train set (High level expansion pack and a motorised train). Maybe a fancy dress costume or character onesie.