A rule of thumb to consider;
a. Are you out for a fly around on a nice day looking at various points of interest etc? A basic service would be fine as it does not restrict you in any way.
b. Are you going from A-B in nice or marginal wx? Ask for a traffic service. It is restrictive in the fact that you shouldn't change heading or levels without informing the controller as you may be subject to coordination with other aircraft.
c. Are you going from A-B in IMC? Ask for a deconfliction service. You will be passed advice/ instructions to assist you in maintaining standard separation from other seen aircraft. After any avoiding action, you will be released own navigation so you need to be able to navigate yourself from the point that you are released after such action. In all the above the aircraft commander is ultimately responsible for avoiding other aircraft.
1 final point. If your routeing takes you through any controlled airspace/ ATZ's you are responsible to obtain the clearances yourself. it's not the controllers responsibility to guess what you need.
Hope that helps.
