First let me say I have zero experience with what I am about to suggest but it's still going to be my suggestion. I have been getting the itch to update my electronics so I have been doing some research...If I were buying a new sonar for the sole purpose to locate fish then I would look really hard at Garmin Livescope. When Panoptix first hit the market I liked the way in which it shows a live picture but it was hard to for me interpret. The new Panoptix Livescope uses the Panoptix technology but the addition of Livescope changes the picture so you can see a easier to interpret picture of what's going on under the water.
My second choice would be Humminbird 360. I like that it shows a real time picture but its not live. I know to some that may not make sense so let me explain. The transducer is constantly sending a signal and getting a return. It will update every few seconds with a real time picture so its real time but it has a delay in the picture because it is waiting for a return signal. Plus it's is not live where you can watch fish swim whereas with Panoptix or Livescope it is a real live picture where you see fish actively swimming on the screen.
As for operation then I say Youtube and Google is your friend. I know when I got side scan I knew nothing about it. Through youtube and google I learned a lot of useful information about sidescan. If you go Panoptix, Livescope or 360 you will have to buy a unit that is capable of using the appropriate transducer. You could always buy the GPS/sonar with traditional sonar and update to the more advance stuff I mentioned later. I am not real sure what Panoptix cost but Livescope is about $1500 and 360 about $1000. You can spend anywhere from $5-700 on a head unit that is compatible but if you want a big screen with tons of other features the price can go up to $2000 for just the head unit. For a ballpark figure of $2-2500 you can get a top of the line new GPS/sonar with any of the three features I mentioned. The price is what's keeping me from pulling the trigger but the more I watch youtube the more my trigger finger gets the itch...Garmin Livescope would be my choice if $ was not an option.