[DeTomaso] Selecting Relays???

[Ken Green]

I need to buy some relays for my relay/fuse panel project.  All I need are single pole single throw (SPST) relays.  I looked at the Hella catalog and they have SPST relays with diodes, with resisters and with neither in the coil circuit of the relay.  The only difference I see is the operating and drop out voltage.  Assuming that I always have a bit above 12 volts, does this really matter?
 
It also looks like I can buy single pole double throw (SPDT) relays of otherwise similar specs for less.  I can imagine that the SPDT relays are less because they sell a lot more and it's a stocking issue?
 
Any suggestions?
 
Ken