WiFi or 3G

Depends on signal strength, really.

I Keep wifi on all day at work, since I have a low signal there. WiFi keeps the minimal things I have syncing up to date, without being so harsh on the battery.

 

Most people seem to think wifi is more efficinet as long as you are connected to a wifi network. I wasn't able to find a defininitive source, but here's a similar thread: http://androidforums.com/motorola-droid/17471-3g-vs-wifi-when-home-uses-less-power.html

 

I'm almost positive wifi uses less power than 3g. But remember to turn it off when you know you're not at home/near wifi so your phones not constantly looking for wifi and draining battery.

 

3g... Because of the spotty connection .

 

What do you mean help? Putting it in airplane mode will block signal to your phone except WiFi. WiFi isn't responsible for sms and calls. Just turn off 3g and not in use or use an app like juicedefender and set up profiles.

 

You can turn off mobile data, and still have the 1x signal, allowing incoming calls/SMS. However WiFI will not download MMS messages, so that being said, 3G is needed for that.

Or you could do what Afnan said, and use JuiceDefender. It's what I use.