@Idelossa,
Six is a great number! Typically, people will do this kind of redundancy with just two switches, so the fact that you have three stacked, you can just discount the third one and utilize it elsewhere. A typical config would be like this:
ESX vSwitch config
vmnic0,3 - Management Network (separate VLAN)
vmnic1,4 - vMotion Network (separate VLAN)
vmnic2,5 - Production Network (VLANs and what have you)
You can run Etherchannel or LACP, but that is not really necessary unless you have high traffic on one link. If you have to choose, I would choose LACP, but that's more preference. You will want to make sure that "notify switches" is turned on in the vSwitch port group settings, so that switches will be notified of state changes in the links.
Physical switch config
switch 1: vmnic0,1,2
switch 2: vmnic3,4,5
This way if you lose a switch or a single vmnic or a vmnic bus (i.e., vmnic0,1 built-in to motherboard) then you will still be live in every fashion.
If you want to use all three switches then I would do it like this:
ESX vSwitch config
vmnic0,1,3 - Management/vMotion Network (separate VLANs for each)
vmnic2,4,5 - Production Network (separate VLANs for each)
Physical switch config
switch 1: vmnic0,2
switch 2: vmnic1,4
switch 3: vmnic2,5
Hope that helps! You certainly don't need the Nexus 1k to be fully redundant!