Leave the batt selector on "Both?" Why? You should trace out your DC wiring and find out how it's designed and installed, first, before you make that decision. The issues are all discussed in that link I sent you, and I know there's no way to to have even started on it yet, so happy reading.
But the "Why?" is because your charger should work with the switch in the off position, as if you were leaving the boat. The charger should be wired to the batteries, not to the C post of the switch. If you need to have the switch ON, you should rethink the wiring. It could be wired to the 1 & 2 posts of the switch, which is just the other end of the same wire as if connected to the batteries.
You also seem to be thinking about using a lot of 120V appliances, although I understand the need for the air conditioning.
It would seem to me that you have two choices, without going "all minimalist"
1. Remain as plugged into shorepower and use 120V appliances like you were at home
2. Start learning to reduce your dependency on 120V (except for the AC).
Or something in between. But if you're only gonna be doing a liveabord, as compared to learning how to use boat DC systems in the expectation that you will eventually "pull the plug"
, then that's fine, too.
Your boat, your choice. Good luck.
In answer to your energy draw, you really need to do an energy budget, also included in my link. West Marine also has one on their Advisors. http://content.westmarine.com/docume...r/Elecbugt.pdf