Like you, I have been working through various classes to, inter alia, minimise the need to take prestige classes (I also give a feat every level which also helps).
My current version of the paladin is probably overpowered (but OK for my games) but here is the list of abilities in case you can draw some inspiration:
Aura of Good (Ex): The power of a paladin’s aura of good (see the detect good spell) is equal to her paladin level.
Detect Evil (Sp): At will, a paladin can use detect evil, as the spell.
Divine Challenge (Su): As a swift action that does not provoke an attack of opportunity, you boldly confront an Evil enemy within sight and that enemy is surrounded by divine light of a shape and colour appropriate to your deity. You must then engage the target by either attacking it in melee or ending your turn adjacent to it in a square where the target is threatened by your melee weapon. If either condition is not met then the divine challenge ends and you also lose the use of the ability on the following round. The divine challenge ends at the beginning of your next turn when, of course, you may choose to use the ability again.
While marked by the divine challenge ability, your enemy takes a -2 penalty to attack rolls for any attack that does not include you as the target or, if the attack has a DC, the DC has a -2 penalty. Furthermore, it takes untyped Good-aligned damage equal to 1d6 plus your Cha modifier on the first time it makes an attack (including, inter alia, casting a spell) that doesn’t include you as a target before the beginning of your next turn. This damage increase to 2d6 plus your Cha bonus at 11th level and 3d6 plus your Cha bonus at 21st level.
A creature may only be subject to one divine challenge at any time.
Turn Undead (Su): You may turn undead as a cleric of the same level as your paladin level. You may use this ability a number of times per day equal to 3 + your Charisma modifier.
Divine Grace (Su): At 2nd level, a paladin gains a bonus equal to her Charisma bonus (if any) on all saving throws.
Lay on Hands (Su): Beginning at 2nd level, a paladin with a Charisma score of 12 or higher can heal wounds (her own or those of others) by touch. Each day she can heal a total number of hit points of damage equal to her paladin level x her Charisma bonus. A paladin may choose to divide her healing among multiple recipients, and she doesn’t have to use it all at once. Using lay on hands is a standard action.
Alternatively, a paladin can use any or all of this healing power to deal damage to undead creatures. Using lay on hands in this way requires a successful melee touch attack and doesn’t provoke an attack of opportunity. The paladin decides how many of her daily allotment of points to use as damage after successfully touching an undead creature.
Aura of Courage (Su): Beginning at 3rd level, you are immune to fear (magical or otherwise). Each ally within 10 feet of you gains a +4 morale bonus on saving throws against fear effects. This ability functions while the paladin is conscious, but not if you are unconscious or dead.
Divine Health (Su): At 3rd level, you gain immunity to all diseases, including supernatural and magical diseases.
Divine Mount (Su): At 4th level, you gain a bonus to ride checks equal to your Cha bonus. In addition, any mount you ride gains a range of benefits:
• uses your saving throws in lieu of its own (including any benefit from Divine Grace);
• shares your Aura of Courage, Divine Health, Holy Shield and Holy Strike abilities; and
• gains temporary hit points equal to half your full normal hit point total.
These benefits last for up to one hour after you dismount but may only apply to a single mount at any time.
Holy Shield (Su): At 4th level, you gain a deflection bonus to your armour class equal to your Cha bonus. At 8th level, you gain the improved version of this ability where it now functions much as protection from evil spell in that it holds evil outsiders at bay. At 12th level, you gain the greater version and grant your protections to all allies within 2 squares.
Spells: Beginning at 4th level, you gain the ability to cast a small number of divine spells, which are drawn from the paladin spell list. Otherwise, this is the same as the cleric’s ability to cast spells, including the option to spontaneously cast cure spells.
Your caster level is the same as your paladin level.
Holy Strike (Su): At 5th level, all attacks you make are treated as being Good-aligned. At 10th level, you gain a +1 sacred bonus to all attacks against Evil opponents and inflict +1d6 damage. At 15th level, you gain +2 sacred bonus to attacks against Evil opponents inflict +2d6 damage.
Paragon of Goodness (Su): At 20th level, your commitment to Good is so strong that your type changes to Outsider with the sub-type of Good (and the appropriate augmented type), you gain damage reduction 10/Evil and the benefits of a continual holy aura that may not be dispelled.
