How are the lights wired right now? Are they on a different subpanel than the main house? Most of the insteon units send the controls over the power lines, but some of the units do both the RF and power line. It's probably best to take a look at that first as that could make a different in the insteon units that you could use. You should be able to get it working, just need to know which of the items that you need to buy for it to work.
If you didn't want to do that you could look at the Lutron, that's all wireless as far as I know and is fairy easy to setup
The other option would be the ones that run the zwave wireless, such as the ones by GE and Leviton. Those seem to me to have more different types of products, so if you wanted to tie a motion sensor in with that it might be easier.
I think any of those would work well - if that's all you are going to do with it, go with the lease expense set you can find and it should take care of. But the big thing about this stuff is that you just keep wanted to expand it. First thing you do is the outside garage, and next think you know you can turn of the kitchen light from your bedroom, then all of a sudden you throw a garage door control in the mix, next thing you know you are using your smartphone to turn on all your lights when you are minute or two away from home. Some of the stuff you can do with it is "cool", but once I started installing mine, I kept finding things that made things easier for me - groups lights in the kitchen together instead of having to toggle 3 different switches, etc.
So really, any of them will work, just take a look around and see if makes sense and you think you would want to expand your system beyond that one controller and what you would like to do with it. That would probably dictate what you want to buy. I find it really handy to be able to turn the porch light on and off from the living room, but that's just my preference. I've got a mix on the insteon and z-wave, and both have worked like champs.
