I occasionally use it on my lap but most of the time it is either in the dock or sitting on my desk at work plugged in. I bought it as a desktop replacement for home but wanted something I could take to work with me as well. Other than discharging it once a month, should I leave it unplugged at work? I only have it on maybe half the time.
Basically, I wouldn't worry too much about it. If you must, here are the considerations:
1) You lose battery life by using charge cycles of the battery.
2) However, you also lose battery life by leaving it at 100%. Ideally, you would have it at ~50% charged all the time.
This creates a situation where you don't want to use the battery because you want to avoid using charge cycles BUT you also ideally want to leave it around 50% charged since that minimizes the battery life you lose for leaving it charged. For devices where you cannot remove the battery, it is generally advisable to leave it plugged in and have it not use the battery since using charge cycles will generally degrade it faster than letting it sit at 100% would. You can alleviate that by occasionally running the battery down (which would use a full charge cycle but may allow the battery to recalibrate).
Anyway, in my mind, it's more trouble than it's worth. I'd advise just not thinking about it and use it in whatever way is most convenient to you. Sitting on the couch? Forget plugging it in. At work in an office setting? Probably outlets around so plug it in. Long commute? Don't care about running the whole battery down because that's why the Surface Pro 2 is portable: it's meant to be used on the go.
