Floyd:
Imoen's my thief so she's only got limited thieving abilities, but enough to get by with by all accounts.
Personally I prefer prefer to keep her in the back line until I need her to disarm a trap. There are 2 main reasons I use my Monk in the front line for detecting traps.
1. sometimes when I'm moving too quick I'll miss one and he'll set the trap off - occasionally he'll take some damage (he's got enough hitpoints to survive, and a gaxx ring to regenerate with) but he's pretty much immune to most of them. If Imoen sets one off she takes a lot more damage or dies.
2. When we encounter enemies, my monk's there in the front ready to pounce, and Imoen's safely at the back. I don't want to rearrange my party every time we encounter enemies - people get in each other's way and it takes longer to get into attack formation.
Hide in shadows/move silently is great as well (although I suppose you could use invisibility potions/spells to do the same - I prefer hide in shadows as it's limitless and can't be despelled). He can move in real close to the enemy; he doesn't have backstab
but he's got stunning blow, quivering palm and other high level abilities such as greater whirlwind and he's quite at home in the middle of the ensuing fight. I used to have Yoshi as my main thief, but he had such bad AC and thac0 that he was a liability after his first backstab attempt and had to retreat out of the way before he could use his bow safely.
I'll often send my monk in, hidden, pick a suitable target (normally mage), have the rest of my party attack another target while I batter the first mage to death, with enough attacks per round that hardly a spell gets cast. Normally we get through most battles without needing potions or spells - I tend to use them as a last resort rather than as a general rule.
The beauty of this game is that there are so many different ways to play it - given my current party, this is the way I like to play it. Another time I'll play it without a monk and find a different strategy.
Also:
Gauntlets of crushing:
Thac0: +4 bonus when attacking with fists
Damage: +4 bonus when attacking with fists