I have a condo in Destin and have been going to PCB and Destin for 30 years. By far the best route I have found is your first choice.
85 South to 185 South RT431 South through Dothan. There are only a few sections that are not 4 lane. Easy drive for the most part and far quicker than going all the way over to Montgomery.
I have a condo 1.0 mile from the baseball fields at PCB and always go the 431 route. Can't give you the side roads I take once entering FL, too confusing, but 431 is the best route.
I think the old speed trap thing through Dothan is a thing of the past. I usually don't see to many cops through there now. I think they pretty much leave you alone now.
PCB is awesome and that 1st route has gotten way better since the early 2000's. We counted the crosses one time on the way to Destin and saw 42 along the route. Readers Digest had that listed at one time as the deadliest road in America. When we go now that way now, we remind our H.S. kids of when we had to pull over on a dirt road and have them pee in the bushes..they just couldnt wait.....those were the days.