Can I use suffixes (な、ね、さ、わ...) before と思う?


I always hear ～なぁと思った, but I don't know if it comes from:

食べるかなーと思った。 or like  
きれいだなーと思った。 or  
寒いなーと思った。

I think this sound なーと思う is so relaxing and so nice, that I want to use it.
But actually I would like to know how is used and where.

Related to it, I was thinking if we can use a suffix before と思う, like:

  * そのパソコンは高いねと思ってた。I was thinking how expensive is that computer (is it ok?)
  * あの道は危なくないさと思う。I think that street is safe.
  * 。。。




I think particles like "よ", "さ", and "ね" sound a little strange before "と思う".
If you think about what you're doing when you say "I think", you're
essentially quoting your own inner dialogue. Using particles that are normally
meant to elicit agreement from (ね), or convey information to (よ,さ), a second
party to a conversation make that inner dialogue sound a little schizophrenic.
It's just not logical in my opinion. On the other hand, particles like "なぁ",
"か", "かな", sound fine.

