Former Sen. Alan Simpson, a Republican, is making the case for a “live and let live” approach to same-sex marriage in a new television ad buy targeting Western states, just as a federal appeals court in Denver prepares to take up the issue later this week. “Whether you’re gay or lesbian or straight, if you love someone and you want to marry them, marry them,” Simpson, of Wyoming, says in the spot. The six-figure buy, sponsored by the pro-gay marriage group Freedom to Marry, is slated to start airing on Tuesday on national cable channels, as well as locally in...