I am going to agree that disconnecting and reconnecting a battery, when leaving it disconnected for long periods of time (and not just a few minutes while changing the battery), is going to be annoying. In that extended period of time anything that was stored in memory is going to be lost, your radio stations gone, that saved driving position gone, any adjustments the ECU had saved gone (even if they are recovered in 15 minutes that many be the extent of your drive) and the list goes on and on depending on how fancy a car you own. Will it harm your car, I do not believe so, but you will have to decide if the annoyance is worth it. On the plus side it will make your car harder to steal.
Batteries last, my last vehicle was a 2003 and I often let it sit for 4-6 weeks and there was no problem or even struggle starting it. So if you are going to drive to the store every couple weeks you may not need to do anything.
If you are talking months and months without use you should probably look into a battery maintainer that plugs into the cigarette lighter outlet. They cost about 20 dollars. Since you have a private garage there will likely be a source of power that you can connect to (light bulb adapter, normal wall outlet, most garage door openers plug into an outlet on the ceiling (you'll just have to get creative with an extension cord).