When you are sending it should show you how much you have.

[jedmccaleb]

No description provided.

[johansten]

Are you thinking about the payment options? I.e., Send as "1000 XLM (5000 Available)"

[jedmccaleb]

This screen

I'd just keep your balances visible how they are on the overview screen

[johansten]

I've experimented with a couple of different layouts, but I'm not sure what the most intuitive way to do this is.

The way it works now is a reflection of the underlying APIs. Paths and path payments are always specified in terms of the receiver, so there's no way of saying "I want to pay exactly N units of asset X, give me a list of the available options".

[MRGiacalone]

How about showing the balance in Lumens right next to the account name (on the sidebar)?