Swallow the xanax. They are made to kick in extremely fast and have a high BA when take orally. plus, the taste would be almost unbearable and in my experience not worth the extra little bit.
as for valium, I have no idea. I'm a xanax/K-pin type of guy.
If you are looking for the highest BA your can always look into plugging them.people think its gay and I've never done it personally but if you are looking to get the most out of them, that is your best bet if you're open to it.