I found this thread from doing a search on the terms 'baritone' and 'strings'. I learned a bit reading through the posts, and I thought I'd add my experiences.
My baritone is a Tele with the Warmoth 24-fret bari neck. When I first put it together, I stringed it up with a set of Ernie Ball Not Even Slinkys. I tuned the guitar A to A and found that the 6th and 3rd strings were a bit flappy feeling and sounding. They worked, but I wasn't totally sold on them.
I just stringed the baritone up with a set of D'Addario Light Baritone Strings -- the EXL158s, 13-62. These work much better with the A to A tuning. All the strings are nice and tight, but not too tight where I can't do bends easily. I am very happy with this set and these gauges. The sound of the guitar is much better now as well. The extra tension made all the difference.