Is there any reason at all to have a stealthy character who cannot use sneak attack, for example a ranger or monk?

Rangers and monks both get hide and move silently but I cannot figure out why I would want to use such abilities unless I had the HiPS (Hide in Plain Sight) feat and only if I wanted to run away in the middle of combat, which usually doesn't work if you have companions.

Also, does anyone know if Bleeding Wound works? I could never verify if it worked or not.

Imo, the only reason to use stealth is if you have sneak attack, but NWN2 keeps saying that it's a great idea for monks, rangers, etc. who don't get sneak attack so then I think about multiclassing but multiclassing weakens both of those classes to a degree that it's no longer worth using them (at least, when multiclassed with rogue and shadowdancer).

Someone please tell me that I'm wrong LOL ;) :D

I think D&D3.0 rules introduced Sneak Attacks as something you get every time you flank an opponent or catch them off-guard; you don't need stealth for the former. I seem to remember Hide being pretty useless in NWN1, though, and of very limited use in NWN2.

As for Rangers and Monks, yes, there is a reason. Roleplaying is an obvious one. Rangers also get access to an animal companion and some spells, which Rogues don't. The Monk, on the other hand, is probably the most powerful base class around once you get a few levels under you belt.

Multiclassing doesn't necessarily weaken characters. You just trade focus for a broader range of abilities, which is kind of a double-edged sword admittedly, but Monk and Rogue are fairly popular choices for multiclassing from what I've seen, and the Ranger to a lesser extent.

Role playing is one reason to have sneak, for sure. In a group situation, it's got uses. Like to, say, keep a druid hidden in the background to make sure heavy hitters go for the warriors first. There are other ideas, too. But in NWN, it's hard to make things work like that. I find myself using sneak with non-rogues in other D&D games, less so in NWN.

Oh, and I find getting sneak attacks from flanking, (hiding not necessary), is effective. Just let a friend engage the enemy first, then have your rogue stand behind the target.

If you're talking about the NWN2 Invisible Blade's bleeding wound, it does work, but I think it got a reputation for being too slow. Like, the battle is over by direct damage a lot faster than bleeding someone out. I don't know how accurate that is.

I'll guess you might know this already, but the way the rolls work on a d20, 6 hide/move silently skill is not twice as good as 3 hide/move silently skill. It's the difference from a roll of 7-26 or 4-23. So you can afford a little trade-off for multiclassing.

Sneaking is useful for scouting out an area. You can leave your henchmen behind and take a look at what's ahead, then prepare for it.

With load/save abilities, its use in single player is rather limited.

In many multiplayer scenarios, it's immensely useful. Lots of servers have randomized encounters, so you'd want to sneak ahead and figure out what there is coming.

Also, not in the OC of NWN or NWN2, but in other modules there are situations where you're best off avoiding combat. Doing a bit of burglary or whatnot.

As far as OC or any of the official campaigns are concerned, I'd agree you're best off putting your points somewhere else.

The only official campaign where it's useful is NWN2's Storm of Zehir, where it allows you to more easily avoid unwanted encounters on the overworld map and sneak up on ones you do want to attack. Other than this, stealth rarely comes up. Even in situations that can be solved via stealth, the game provides little incentive for a non-violent solution when combat will suffice. In the few cases where stealth stands out, you can just cast the invisibility spell instead (a Rogue can use the "use magic device" skill and stock up on scrolls) to get the same result.

Generally speaking, the big advantage of multi-classing Rogue is his evasion skill and his large number of skill points and class skills. Rangers and Monks already get evasion (just much later) and have a fairly decent class skill list of their own. Multi-classing rogue doesn't make much sense for them.

If you do want to multi-class with the Rogue class, then the best candidates are Fighters, Barbarians, and (perhaps surprisingly) Paladins. The heavy warriors benefit enormously from the diverse skill selection of the rogue, greatly enjoy his evasion ability, and are in the best position to put sneak attack to its maximum potential.

Yes, that's true for NWN2 which uses the excellent D&D3.5 rules.
In NWN1 using the D&D3.0 ruleset, a decent Ranger has to take few levels of Rogue and Fighter. No longer needed in NWN2.