Good point Johny. Actually, I have series parallel set up for 12 volts, so it increases the total amp hours, but the total system voltage remains at 12 volts. My small home is wired for both 110 VAC and 12 VDC. I went with 12 volts rather than 24 or 48 volts because there are so many appliances and devices available that will run directly off of 12 volts, rather than going through a DC voltage converter or an inverter. Most of my lighting also runs on 12 VDC. For example, in my kitchen/dining area there are four Ikea pendant type light fixtures, two of them run on 110 volts AC and the other two on 12 VDC, the fixtures are identical except the bulbs. The wiring consists of two strands of 00 wiring. It's important to note that the house is small, so the voltage drop is not that significant. All of the task lighting is 12 VDC, using a combination of 12 volt incandescent, fluorescent and LED lights, though I'm converting to LED's as finances allow.
One of the task lights that I really like are called littlelites
http://www.littlite.com/ They are favored by musicians, and they come with a lifetime warranty. These tiny lights are super bright, perfect for a reading lamp. They're offered in incandescent, halogen and LED configurations. Some other off-grid folks turned me on to them. Lately I've been using some LED light strings, which are fine for general purpose or mood lighting.
Getting back to the batteries, I maintain a number of solar powered radio repeaters, and we use lead acid batteries exclusively for our systems. I tried some of the AGM batteries, but found they didn't last as long as conventional lead acid batteries.