OP, a couple questions:
Have you ever taken Tramadol on it's own recreationally (or otherwise)?
Have you ever had a seizure?
Do you take any other meds, especially those that lower your seizure threshold or ones that, in combo with tramadol, can cause serotonin syndrome (ssri's and dxm, for instance)?
If you've never had a seizure, don't take anything that lowers your seizure threshold AND don't take anything that can cause serotonin syndrome when combined with tramadol, I'll tell you what I do: I find 250-400mg of tramadol + my bupe dose provides a wonderful effect.
The dose of tramadol you'll need to enjoy it in combo with suboxone depends on you though. As you know some love and other's hate tramadol. The same goes for the combo with suboxone. The dose that works for you in terms of the tramadol can only be determined by trial and error.
I don't mean to be a dick, but you really could have figured out what a good dose of tramadol+suboxone would have been from other threads... but we're past that, so moving on...
Chances are, unless you've very sensitive to tramadol's effects, you'll probably needs a minimum of 200mg to enjoy the combo. I'd start with 50-100mg of tramadol, just to be sure you don't have any negative reaction to the combo. If that works try 150-200mg the next time. And if you feel comfy with it, and still want more from the combo, try 250-350 for your third try.
btw, the dose of tramadol seems to be independent of your suboxone dose (e.g. doesn't matter if you take 16mg or 2mg of suboxone). fyi though I take 4mg 2x/day.