My basic approach is to keep the starting battery for all the OEM stuff, and the auxiliary battery for all the add-ons (2M, Fridge, Inverter, Karaoke machine, and all auxillary 12v and 110v outlets). But I guess if you want to play music continuously at camp, then you'll need to keep an eye on that starting battery, or get a little portable unit and plug your Ipod into it (assuming you have an inverter).
I've always had my winch wired to my primary battery, I think mostly because of the direct relationship to the alternator for extra power if needed.
1976 FJ40 - green and mostly stock
1996 FZJ80 - not so stock