Some interesting points made which I hadn't heard before (although the difference in battery life may be fairly minimal).
In general, it's always better to limit time at a high SOC and to charge at a slower rate if possible to preserve battery life. So if your normal routine is to charge every night, and your battery gets to the SOC target many hours before you normally leave, try charging at a lower amperage that still gets you to the target before you leave.
This is especially true with PHEVs, which have such a small battery it's hard to avoid getting to 100% way too early.