You said you aren't interested in dual classes, yet you have two in the party.
Fighter/Druid - Insane lends itself to multiclasses. At the very least, I'd turn the dc f3/druid into a mc - don't forget that you get bonuses to your attacks/round at fighter lvl 7 and 13. A mc f/d on insane will easily surpass lvl 13 in both classes, assuming you have both expansions.
Paladin - I'm not sold on having two blunt weapon proficiencies. Why not just one? You could use a ranged weapon (sling/darts or crossbow?) and axe in the early game, add mace or flail, then add longsword. You should hit lvl 6 in the Vale, and thereby have specialization in a blunt weapon to clear the skeletal undead.
Fighter/Mage - I'd put a blunt weapon in as the third proficiency, not the fourth. Hammer is fine. You could also make this character a gnome fighter/illusionist. One more slot per level will make a difference to a melee mage (extra mirror image), although you will miss out on a couple of decent necromancy spells.
Ranger - are you saying that you can get the extra attack with two-handed weapons? That is not the way it is supposed to work - can you verify that? Bow is good, greatsword is fine, but I'd add a blunt weapon because so few enemies have resistance to bludgeoning damage; a ranger has great offensive melee capacity and is ideally suited to coming in as an untargeted 3rd melee option against tough melee enemies. I'd also do one of halberd and spear, not both. With greatsword, you will still have a choice of two two-handed weapons - that should be enough. I do prefer spear because you find two good non-random spears, and I can't recall any fixed halberd drops - you may have to buy a decent halberd. You may wish to add longsword at some point because there are so many good ones and you would get the racial bonus.
Thief[7]/Cleric - Good enough; just make sure that you regain thief skills by DE lvl 5 (camp on DE lvl 3 if you have to). I'd put all the skill points into find/remove traps and open locks. The bard will cover pickpocketing and this character won't be scouting around much - the ranger can do that if you need it, and Sanctuary can be used for that purpose too. I prefer good clerics, but neutral clerics do get access to some "evil" cleric spells that good clerics cannot use - I've never found the reversed healing and raising spells to be all that useful because they require a touch attack and have really long casting times; both of which just cry out for disruption. Cloud of Pestilence is a good spell, and Circle of Bones is ok. An evil cleric is a pain if it has a really good turn undead skill - instead of destroying undead outright, you will merely control them for a short period of time, after which they turn hostile again. I believe evil clerics also lose access to the major healing and resurrection spells, so I wouldn't take an evil cleric unless I had a second, non-evil, cleric in the party.