I'm currently at 62 friends and, frankly, I'm finding that overwhelming. There is simply no way to keep up with everyone, especially with the cap of opening 20 gifts per day. I haven't ended a day yet without a backlog of at least 24 gifts I can't open.
For now, I'm focusing only on a handful of friends at a time, namely my spouse and a few others with whom I play almost daily. Until Niantic fixes the friendship level sync bug, we're coordinating who does something first each day (the most reliable way to do that is opening a gift). Once that friend levels up, we'll have our sync day and then resume towards the next goal.
I really can't handle the logistics of doing that beyond 4 or 5 people, so that's my main focus now. All other friends will have to level up as it happens through gifts (if we ever get to open them), raids, etc. I imagine once I have achieved Best Friend status with those 4 or 5, I'll see who's the next batch through regular interactions and start focusing on those.
Or, Niantic could fix the level bug and make the gift cap match the maximum number of friends (200), and then we could just play the game without stressing over it. Just a thought.