Yes, they both work well for aoe tanking. I recommend alternating them on trash pulls when they are on cooldown.
Recklessness effects damage shield procs, yet doesn't use the charge. (this also applies deep wounds.) Be careful with Recklessness if you your mobs hit hard/fast due to the extra damage taken. I'll also use recklessness for threat-sensitive boss fights where I'm not at risk of dying quickly.
afaik, Retaliation only procs of non-blocked, or non-avoided hits so it's proc rate is lower then you'd think.
I don't agree that warriors have problems aoe tanking, assuming the mobs are hitting the warrior. Maintaining a TC/shockwave & tab-cleave rotation can hold threat off all other non-tanks, assuming relatively equal gear.