Election issues - voting for the main parties "tactically"?

I can only give you my perspective from across the pond. In 1968, when 20 was not yet old enough to vote in the U.S., there were half a dozen or so splinter parties on issues like the war, police brutality, civil rights, etc., including a Peace and Freedom Party and a separate Freedom and Peace Party. Except for one challenge on the reactionary side by George Wallace, all these options took votes away from Hubert Humphrey, the Democrat who, while stubbornly defending the police action (no war had ever been declared by Congress) in Vietnam, was still a member of the very liberal Americans for Democratic Action (sort of like a grups' version of SDS) and would have been a far better "lesser of two evils" than Tricky Nixon. Ever since I became eligible to vote, I have always voted for the Democrat in presidential elections. To do otherwise would be like accessory to treason, if only in the pive sense as befitted Nancy Pelosi's refusal to pursue impeachment of the Bush regime.