Sanitizing 50 beer bottles sucks. Buy this:
http://www.northernbrewer.com/vinator-bottle-rinser. Arguably the best $20 I've ever spent on brew equipment. I've got about 70 batches under my belt now and it only took a handful of batches to realize that dunking and draining 50 bottles every bottling day, like you said, is tedious and painful on the back. I can now sanitize a batch worth of bottles in under 5 minutes and I don't require 2 Advil at the end. Sanitize using this and then I put the bottles on this:
http://www.northernbrewer.com/economy-bottle-tree. LIke others, I attach the bottling want to the spigot of my bottling bucket. I make my priming sugar solution first, then, while that's cooling, I sanitize my bottles and put them on the tree. Dump the priming solution into the sanitized bottling bucket, rack the beer into the bottling bucket, bottle and clean up. Alone I can do it in about 75 minutes. With a buddy, easily under an hour.