I have some credit with Midwest and I'd like to pick up something worthwhile. Any suggestions on a good investment after my first brewing kit?
Is a bottle tree worthwhile?
I say a bottle tree can be done without.
You might consider at least two different things. Firstly, you could keep the credit and use it towards a digital temp controller for the freezer you will most certainly will want (need).
Second, maybe an ATC refractometer or a bench capper that can handle a wide variety of bottles. While the wing-capper will suffice I think they are a real PITA to use for any really serious bottling sessions.