I can't wait to start adding in the mutex contention to our tests, remove our custom graceful http shutdown library, compile 15% faster, start using context within our queries, write custom comparators [I needed this just last week! We had a type that already implemented the sort interface, but I needed to sort it by a different key in this one-off] for sorting, and have a much better time debugging JSON unmarshalling.
And those were just the big pieces I noticed that will be an immediate improvement!