@jeffdrex, welcome to RAV4WORLD.
The 80% trips up a lot of people. The software keeps a buffer at the top end and at the lower end. It's probably best to ignore these buffer areas (since we can't exceed those limits) and just think about the car as being between 0-100% charged. With that in mind, if you plug in the car and let it charge to completion, you will have 100% of the battery capacity. However, if you use the Charge Mode, the car will limit the charge to 80% of the useful capacity. I suspect that this was due to the fact that it's easier to charge a depleted battery to about 80% capacity, which should be enough for most people needing to use the Charge Mode. The software could take it further, but efficiency comes into play, and instead of taking that hit, the designers chose to limit Charge Mode to 80%.
It's better if you don't charge the car to 100% if it's going to be sitting for awhile. My understanding is that it's part of the chemical process and a fully charged battery is less stable. I guess that if you fill it up to 100% and then let the car sit, it would be like filling up an ICE vehicle and then leaving the gas cap off. You might lose some of the charge that you put into it. However, at something less than 100% the battery is better at retaining the charge for a period of time. It also might be detrimental to the health of the battery if it's "stored" at 100%.
You also need to consider how you're going to use the car when you do drive it after charging. If you're going to be using HV mode for something like an extended trip at highway speeds, it's better to have something less than 100% charge so the HV system has a place to put excess energy. The car will run fine, but it might have to throw away the excess energy if there is no place to put it. Lots of people will charge the night before and then start their trip in EV mode. If you want to save the EV mode for the destination, you can manually switch to HV after you've used the EV for a few miles. If you don't care about having any EV capacity left, you can drive in EV mode until the battery gets low and the car automatically changes to HV mode.
There are other threads talking about why the Owner's Manual recommends unplugging the charge plug after it has finished. The thought was that the 12V auxiliary battery continues to provide power to the charging CPU even after charging is complete. While it would be a slow drain, it would be a drain and the HV battery will only charge the 12V battery when the car is in READY mode. Further investigation by dedicated RAV4 owners with ScanGauges found that while the HV battery is being charged, there is a charge also going to the 12V battery. However, it was also found that after charging is completed, the charging of the 12V battery also stops.
You asked about leaving the car plugged in for 12-14 hours, but did you mean after the completion of the charge? I also charge at 120V overnight and don't always go out right away to unplug. However, with the potential drain on the 12V battery, I try to unplug within a few hours of completion.
Regarding topping off after each trip, my understanding is that Li-ion don't mind being topped off. Unlike the old NiCad batteries, there is no issue with the battery forming a memory and a reduction in capacity. I usually take pretty short trips around town and only need to charge every 2-3 days. It's nice to have the ICE as a backup so that I don't have range anxiety, so I just charge when I think I might need to and not worry about starting off with a full charge. If I regularly drove 30-40 miles a day, I would be recharging every day. I guess it comes down to personal preference. Doesn't sound like it would adversely impact the HV battery to be charged regularly, so do whatever works best for you.
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