This is a tough question to answer because there are often so many other variables to consider. But, all things being equal, let's get to the heart of your question which is an assumption: Is it bad to constantly charge/recharge (otherwise known as "cycle") your battery?
Answer: No (caveat: any modern battery)
There's a persistent concern with (rechargable) battery cycles because of NiMH (nickel metal hydride) batteries. Those are still very prevalent in society (think AA and AAA batteries).
But modern laptop batteries are almost always LiOn (lithium ion) - and even more modern: lithium polymer - batteries. Those batteries are largely immune to the "cycle" effect which plagues NiMH batteries. When laptops first came out with NiMH batteries, people noticed the batteries developing "memory" problems. (i.e. New battery charges to 100%. Then you drain the battery to 90 and recharge. Only charges to 99.5%. You drain again to 85 and then it recharges only to 99%, and so on).
Lithium batteries are largely immune to memory issues. Instead, they just decay as a factor of age and heat. So, Nicole's point about taking out the battery (if possible) is a good one to let your laptop just run on AC power.
Additionally, as noted elsewhere, modern laptops now have smart charging systems to bypass charging the battery when full. Older laptops (of even just a couple of years ago), often did not have this ability.
If you look at Apple's battery information page, you'll see it says its batteries are estimated to have 1000 full cycle lifespan. If you fully charge/discharge your battery four times a week, you'd be at 80% battery life in about four years.
TL;DR: Use AC power if you can. Don't worry about battery cycling. Minimize heat.