Anyone know what Gauge wire I should use for hooking up my electronics in my boat? I'm running 2 12V Batteries (In series) to a Switch panel, then from the switch panel ill be running 4 Gangs (Trolling motor, fish finder, Bilge Pump/home made live well and Stern+Nav Lights)

These are the batteries im using btw

http://www.canadiantire.ca/AST/browse/4/Auto/3/Batteries/MarineBatteries/PRDOVR~0102799P/Group+27+Starting+and+Deep+Cycle+Battery.jsp?locale=en

6 gauge is what everyone recommends. Although my boat came stock with 8 and I have had no problems running a 24v system with it, if I ever had to redo it, or was starting from scratch it would be with 6.

So should I just run 6 gauge through the whole system? I'm just over thinking things because not everything draws the same amps (like my trolling motor is 45ish amps and a fish finder would be around 10)

You should not run the depth finder and the trolling motor with the same battery. The motor will cause interference. 

As Scott F said, run the graph off a separate source. 6ga is way overkill for a graph, most of the power cords that come with them have tiny wires, I am thinking like 16-18 ga.

I'm thinking the trolling motor should not be wired thru a switch panel but direct to the battery with 6-8 ga and a dedicated breaker inline.  The other accessories can be wired to the switch panel with much smaller wire such as 12-18 gauge. Run something like 10 gauge from the panel to the battery.  On one of my boats I have two Lowrance DSI units and Minn Kota connected to the only battery in the boat and no interference FWIW. 

In my experience humminbird electronics have more issues with interference than lowrance.  I have a mark 5x hooked to one of the batteries in my 24v system and it has no interference issues at all.  But paranoia got the better of me when I was wiring in my Elite 7hdi and I ran the wires on the opposite side of the boat directly to the cranking battery rather than the switch panel.  I have no interference on that one either, and peace of mind.

All above is correct, and I might add one note.  Years ago, I wired a cheap setup, by purchasing some 16 to 20 ft

jumper cables, then cut off the ends and put on battery connectors, labled one pos and the other neg.  It worked well

for many years.

5 speed trolling motors will not cause interference with a depth finder in they are hooked to the same battery.

 

Find out what the max current draw for your motor will be and wire and fuse accordingly. 6AWG and a 60 amp breaker will be good for most motors.

 

For all other accessories. I would would run a 10 AWG wire, with a 30 amp breaker,  from the battery to the main post on the fuse block.

On the fuse block I would run 14 AWG wires with 15 amp fuses to pumps and other heavy loads like accessory plugs. The I would run 16 AWG wires with 10 amp fuses to all electronics and lights. I think Humminbird wants 3 amp fuses on their finders. I would still run the 16 AWG wire so you wont get voltage drop.