SPOILER
How Spike died was incredibly noble and although bringing him back would kind of rui nthe significance of it, I won't mind that much. The Shanshu Prophecy makes the most sense because having two vampires with souls on the same show may not be necessary. Becoming human will (and has, "I Will Remember You") make Angel considerably weaker, and since he is the title, character, I am thinking they will give this priviledge to Spike. It will also bring good dialogue and events with Angel trying to comprehend how Spike was technically "more good" than he was, especially since he originally wanted to use the amulet and it could be him. I cna just see Spike walking into Wolfram and Hart in broad daylgiht in either the fina lmoments of the Season 5 premiere, or the end of the teaser in 5.2 and saying something like "Well, Lookee who's human!". Hopefully this will prove to be interesting and maybe they will even show the clip of Spike dieing in the "Previously On" sequence at the beginning. When I meet J. August Richards this August, I will see what I can get out of him regarding Spike.