I found that using Pantene Pro-V Ice Shine conditioner SERIOUSLY helped with Samson's tail. Use that and braid it and it should stay soft for days. It worked on my halfies tail anyway and he had PLENTY of tail! Not to mention it makes it nice and shiney =D
After washing his tail, I'll put the conditioner in and then leave it for a few minutes (usually while I'm washing his mane). Then i'll rinse it off (while letting the conditioner set into the mane). =D It makes their tails really slick though so be sure to rinse extra well.