Please excuse my ignorance, but is it ok to use different gauge wires for different speakers. I ran out of 12 gauge and had some left over 16 gauge that I was going to use for my fronts (only 4' run). In theory I don't think it should have an effect, but I just want to get an opinion from someone more experienced. Thank you.

A 16 gauge wire is quite thin. You could just buy some inexpensive 12 gauge zip cord for a few dollars.

Edit: As sprung2 wrote, the 16 gauge wire would work fine for 4 feet. Here is a table for maximum cable speaker length with respect to size and impedanse: http://www.roger-russell.com/wire/wire.htm#wiretable

Please excuse my ignorance, but is it ok to use different gauge wires for different speakers. I ran out of 12 gauge and had some left over 16 gauge that I was going to use for my fronts (only 4' run). In theory I don't think it should have an effect, but I just want to get an opinion from someone more experienced. Thank you.
16ga is fine for a 4' run.

Usually a question like yours starts a spirited discussion:D There are many threads on wire size and many opinions. Do some searches whenever things are so slow you you need an alternative to watching the grass grow or you just want to watch grown men argue.

Cast my vote for 16 AWG and don't worry if the runs are different lengths.

Thank you guys. I just wanted to make sure I wasn't causing any electrical problems by using 12 gauge for surrounds and rears and using 16 gauge for fronts. You have answered my question. You guys are great. Thanks again.