My group currently has a second wind focussed Warden (level 27) and it's awesome. We get expertise and robust defenses for free as a campaign rule. His NADs are a little low but when he second winds, which he gets 3x an encounter, they get bumped up 7 points to where he's nearly unhittable. It was built at level 27, so the order of feats might be a little different and a few of the lower level powers could be better chosen.
I wouldn't think of any other martial class besides Fighter because of Hindering Shield... it turns almost every attack a Warden has that doesn't already slow or immobilize into an attack that does! That gives you the Crippling Crush bonus damage and makes you even more sticky.
The frost cheese was put in because is synergizes really well with Icewrought Sentinel and Hindering Shield (which mean that every attack but his MBA slides 3 and slows.) It's super sticky and self reliant and that allowed our leader to all but ignore heals with their build.
BTW, Eternal Defender rocks, giving reach 2 and a Mordenkrad in one hand! I'm sure you can go for a more defendery build, but this one plays as a one man army. The adjusted second wind number is 83, 166 when bloodied due to cloak of walking wounded.
====== Created Using Wizards of the Coast D&D Character Builder ======
Secund McWindy, level 27
Dwarf, Warden, Icewrought Sentinel, Eternal Defender
Build: Earth Warden
Guardian Might: Earthstrength
FINAL ABILITY SCORES
Str 25, Con 25, Dex 13, Int 12, Wis 17, Cha 10.
STARTING ABILITY SCORES
Str 16, Con 16, Dex 11, Int 10, Wis 13, Cha 8.
AC: 45 Fort: 38 Reflex: 35 Will: 36
HP: 239 Surges: 18 Surge Value: 66
TRAINED SKILLS
Nature +21, Endurance +25, Athletics +23, Perception +21, Heal +21
UNTRAINED SKILLS
Acrobatics +12, Arcana +14, Bluff +13, Diplomacy +13, Dungeoneering +18, History +14, Insight +16, Intimidate +13, Religion +14, Stealth +12, Streetwise +13, Thievery +12
FEATS
Level 1: Crippling Crush
Level 2: Sudden Roots
Level 4: Dwarven Weapon Training
Level 6: Toughness
Level 8: Wintertouched
Level 10: Battle Awareness
Level 11: Hindering Shield
Level 12: Earthstrength Defenses
Level 14: Shielded Resurgence
Level 16: Armor Specialization (Hide) (retrained to Second Skin at Level 21)
Level 18: Dwarven Durability
Level 20: Lasting Frost
Level 21: Earthstrength Might
Level 22: Enduring Font
Level 24: Rapid Wild Defense
Level 26: Epic Recovery
Feat User Choice: Weapon Expertise (Hammer)
Feat User Choice: Robust Defenses
POWERS
Warden at-will 1: Weight of Earth
Warden at-will 1: Thorn Strike
Warden encounter 1: Roots of Stone
Warden daily 1: Form of Winter's Herald
Warden utility 2: Nature's Abundance
Warden encounter 3: Burst of Earth's Fury
Warden daily 5: Boiling Cloud
Warden utility 6: Treacherous Ice
Warden encounter 7: Guardian's Pounce
Warden daily 9: Form of the Oak Sentinel
Warden utility 10: Spiritual Rejuvenation
Warden encounter 13: Stormhowler's Strike (replaces Roots of Stone)
Warden daily 15: Form of the Crushing Mountain (replaces Boiling Cloud)
Warden utility 16: Fortress of Stone
Warden encounter 17: Warden's Lure (replaces Guardian's Pounce)
Warden daily 19: Form of the Stonecrusher (replaces Form of the Oak Sentinel)
Warden utility 22: Renewal
Warden encounter 23: Darkforest Vines (replaces Burst of Earth's Fury)
Warden daily 25: Form of the Entangling Spider (replaces Form of the Stonecrusher)
Warden encounter 27: Glacial Hammer (replaces Stormhowler's Strike)
ITEMS
Heavy Shield, Gloves of Ice (epic tier), Iron Armbands of Power (paragon tier), Frost Mordenkrad +6, Elderhide Armor of Enduring Health +6, Cloak of the Walking Wounded +5, Boots of Quickness (paragon tier), Circlet of Indomitability (paragon tier), Belt of Mountain Endurance (paragon tier), Ring of the Fallen (paragon tier), Ring of Personal Gravity (paragon tier), Strongheart Tattoo (paragon tier), Battle Standard of the Hungry Blade (heroic tier), Siberys Shard of Merciless Cold (epic tier), Foe Binder Ring (paragon tier)