Ok, I'm a little confused. When is the appropriate time to say tornare and when should I use ritornare. I thought they both mean basically the same thing (to return or come back) but I hear people using them selectively.
Can anyone explain?

Around here, they are entirely interchangeable. It might be different elsewhere. Every little pocket of Italy has its language idiosyncracies.

Same here- use either one.

Seems to me that around here (although my circle of friends tends to be from all over Italy) tornare gets used in a more casual sense, like returning from the market... and ritornare carries a little more weight or emphasis.

Or could just be that I'm subconsciously imposing english syntax tendancies on a language I'm still in the process of internalizing.

Tis' true though that I've never been corrected for using one or the other at the wrong time... I can't say the same for words like pieno and ripieno or coperto and ricoperto...

I have tried to pay attention to the difference, and I think there is one, but maybe this is completely arbitrary (?).
I have moved back and forth between Italy and the US a lot. I would say in a sentence, for example, "sono tornata in Italia questa volta per lavoro", on the other, before I left Italy in January I may have said to someone, "si, ritorno in Italia a Giugno". I don't even know if that makes any sense... I guess ritornare implies its not the first "tornare".

Jenna, you said it correctly both times.
You use "ritornare" when you imply that you have already been there and come back at least once(as there is the prefix ri-, like in the English do and re-do), and "tornare" when you come back once.

Very often they are interchangeable in the common language, but sometimes they are not.
See for example "ritornare qualcosa" (to give back something), like for example:
- ritornare il modulo compilato
- ritornare un libro ricevuto in prestito
- ritornare del denaro

Anyway, when you don't want to emphatize or stress the fact that you have already been in that place, you just use "tornare".
When you are talking about coming and going, use both "tornare" and "ritornare" to emphatize the outgoing and ingoing traveling action.

As very often happens, there are more appropriate ways to speak but in the common language they are interchangeable and nobody is gonna notice if you use "tornare" only.

You use "tornare" when there's no movement involved, like "sono tornato a seguire il calcio" meaning something like "I'm back to following football" (after a period when you couldn't care less).
You don't use "ritornare" in this case.

When there's movement involved, it's the same difference. You can use "ritornare" even when you're back from somewhere for the first time.
I'm going to Vilnius on Friday "e ritorno a casa dopo 10 giorni", even if I've never been to Lithuania before.
"Tornare" is more common because it's shorter.