Find a LARS map - the airfield books have one. That will give you a pretty good idea of who to talk to.
The debate about whether to speak to anyone has been going for ever.
Personally I think it can be useful to talk to units that cant provide a radar service because they can warn you of known hazards on your route (are you sure you have read all the NOTAMs, mauves, and there have been no pop up NOTAMs since you last checked), and it does enable you to form some sort of image of what other traffic is doing - of course if you dont participate you will also not enable others to form a picture of what you are doing.
Just one example; when I do aeros I will always call aeros between 3,000 and 5,000 in the vicinity of X. Now that gets called to anyone passing over X; could it avoid a collision one day, who knows but it takes me seconds to make the call so I think I will go on doing so.