This was my response...
I vote the issues when it's effective. I vote the party line when it's necessary.
Anyone who really knows how politics works in this country knows that it's far more complicated than this question makes it seem.
Voting your conscience in local elections (ie voting solely on the issues) is effective and lays the groundwork for an eventual future where the national two party deadlock will be finally be broken.
Local election candidates from alternative parties actually have a decent chance of winning those offices.
However, on a national level, as stands with politics currently, such so-called "conscience" and/or "protest" votes for alternative parties are not only a waste of time, they can actually be dangerous.
Like it or not, right now we have a two party national system.
But that doesn't mean it is necessarily a horrible thing. And it doesn't always come down to the lesser of evils.
What it does mean is that we have to understand that this nation is made up of many ideologies.
Excluding matters of civil rights (which, IMHO, are non-negotiable), all of those ideologies must, at least, be heard and respected in order for any President/Congress/Senate to govern effectively.
Ultimately, it comes down to what's best for the country at large.
And, for the most part, the majority can choose the direction that should take.
Voting for the cream of the crop of the two party system is always a step in the right direction to swing the tides without stepping on the desires of some of the people too harshly.
And change can be affected.
But not when we fritter away precious votes because we didn't get everything we wanted out of a particular party.
Some choose not to believe or acknowledge the "Nader Effect", but the fact is that voting for alternative candidates who don't have a snowball's chance in hell of ever being elected, ruins the chances of good candidates who actually could be elected.