I think that my favourite smell of spring is lilacs. I have been waiting for a while now for mine to bloom. The ones in town always bloom a little earlier than mine do, and it makes me impatient when I drive through the city and see all those pretty purple flowers everywhere. Happily, mine started to open up in the past couple of days. I imagine they were just waiting for the sun.
There must be a couple of different kinds of lilac on my yard, because one kind blooms and then once they are done, the other bushes start. That just means I get to enjoy them for longer. And then, at the barn, there are miniature ones, and they bloom even later! It just seems to make spring last a little longer, before turning into summer. But then I get peonies, so it is a good tradeoff.