Quick question: Would it be better of for the battery if I leave my phone charged for 8 hours at work or should I just charge it at home overnight? I don't have issues of running out of juice but rather concerned about the lifespan of the battery and/or conditioning.
If you want to go to the trouble of nursing your battery for the longest lifespan then charge before reaching 40% and removed from charging before 80%. You could stretch battery lifetime to perhaps 8 to 10 years. However never let the phone get above 95 degrees F. High temperature destroys Li Ion batteries even if phone is off. So no leaving in hot car.
Keeping the charge level between 40 to 80% is a lot of management. You will have to keep multiple chargers or carry one with you. And you won't get all day use on a charge. Since replacing the phone within three or four years is likely you are doing a lot of work for the second owner of the phone. Additionally if past warranty a battery replacement is not that expensive.
Not worrying about charging and just doing it whenever will still have the battery lasting well past 4 years so it's up to you how anal you want to be about charging. Apple has made the phone charging logic very robust such that no matter how you charge it, you will get good life span from battery.
Recommend you use the phone, charge it as you need to and not worry about extending battery lifespan.