hmmmm... i'm not a fan of warrior weapons simply because it really does make your entire army very single-minded. more oftend than not, a combined assault force + rapid firing platoon can solve most problems! a whole hoard of screaming madmen, while good fun, kinda gets blown to little bits before it does much damage!
ogryns too are a leary option. eldar have a tonne of S8 weapons and so they make a huge mess of ogryns. (who can't take carapace armour either!) a single shining spear exarch w/star lance can crush half a unit of ogryns by themselves for example!
also, for the valkyrie to work, you'll need the drop troops doctrine as the very sub-par storm troopers are the only other unit capable of taking one! (and yes, they are indeed a dedicated transport!)
iron discipline is killer for any guard list; regroup even when below half and no modifier for being below 50% starting strength? yes please!
combined with die-hards, your troops will stick around till the time of ragnarok decends! (i once had a single guardsman stand firm against a lictor + 2 ravenors + 8 genestealers + 12 hormagaunts! too bad it ment i couldn't shoot the buggers though as it was my turn next...)
veterans is a must IMHO for an assault/close combat guard list. those hidden power fists will make your units deadly, plus the ability to combine shotguns & close combat weapons in the same squad means along with upto 3 special weapons means you've for once got a very flexable unit!
oh, and for your 'artillery', i suggest a pair of griffon mortars w/infernus shells... rude, just plain rude!
cheers!