Tyrant: You should only take Venom Cannon OR Warp Blast; you can't use both at the same time. WS and I upgrades should always be customized to your enemy. Against Eldar, take +I, against commanders, take +WS, and stuff like that.
Warriors: I usually use the biomorph tables; sometimes I can save a few points on WS, BS, and I if I don't need them. You may want to take a few less Warriors, and put in a Carnifex or broods of 3 Warriors with wings and Venom Cannons (Heavy Support and Deep Strike... heh heh... Hammerheads better watch out).
If your Gaunts have a ranged weapon, take the Spinefist. All of them kinda stink, so you might as well take the least expensive. Again, see what WS and I upgrades are most appropriate.