Having just written a book about oxytocin, I have to chime in here, even though I'm quite late to the party.
First, inhaling oxytocin absolutely crosses the blood/brain barrier to affect the centers dealing with social interaction. cf the many experiments by PaulZak, pauljzak.com. The bbb is kind of an outdated concept. A lot of researchers are testing oxytocin for social anxiety, autism, schizophrenia and depression, and there are documented effects from inhaling, including increased empathy, trust and generosity.
Second, MDMA has been show to cause elevated levels of oxytocin. It probably affects the brain in the same way that being with someone you trust does, by provoking an oxytocin release. Therefore, the drug makes you more open to trust and connecting with others. I think someone else has posted a study or two; just go to scholar.google and search for Methylenedioxymethamphetamine +oxytocin.
My understanding is that a solution of pure oxytocin in saline is only stable for a short time; I'm wondering if it would last for an entire evening.
The effects of oxytocin by itself may be subtle and seem to depend a lot on your environment. If you're around other people who are open to connecting with you, you're more likely to feel the oceanic effect.
Finally, don't feel bad if you get oxytocin confused with the pain-killer. My mom still can't understand why I'd want to write a book about oxycontin.