Not sure where you are sailing, but having AIS is a lot of fun. I run AIS receive out of my VHF to my GPS Chart Plotter. The end result is that I see every ship that goes by that is commercial or AIS send/receive. It gives you the ship heading, speed, name, and port of call among other things. My GPS also has a fishfinder ability, which I haven't bothered to hook up yet. Eventually I may do a thru hull transducer so I also get Temp readings.
My GPS is a Garmin 441s. It is an older model and you can probably find it used or cheap.
My VHF is a Standard Horizon 2150.
It may be worth a look as that is a pretty cool instrument set-up.