Taking a different class/PrC every level?

[faircoin]

Four party members:

Sorcerer
Rogue
Fighter
Cleric

These are their first levels, as well as the party roles they want to fill. They want to be competent at high levels (around tier 3, normal play). How would you go about their 20 level build, if you had to take a different class/PrC every single level?

[Zombimode]

Its easy for the rogue and fighter since they are not dependent on abilities that are tied to class levels.

Its practically impossible for the cleric and sorcerer. I don't know of any caster PRC available at 2nd level. Thus they would have to take levels in other base classes (or paragon classes, which don't help in this regard either) which would not advance their core class features nor would it help them to enter relevant PRCs.

[Diovid]

Its easy for the rogue and fighter since they are not dependent on abilities that are tied to class levels.

Its practically impossible for the cleric and sorcerer. I don't know of any caster PRC available at 2nd level. Thus they would have to take levels in other base classes (or paragon classes, which don't help in this regard either) which would not advance their core class features nor would it help them to enter relevant PRCs.
On the other hand, that might actually be a good thing seeing as that would reduce the discrepancy of power between the characters a little.

In general though I think it would be a nice challenge. The rogue takes a level of Factotum, Urban Ranger, Swordsage etc.

The Fighter takes a level of Barbarian, Warblade and Crusader for example.

As said, the casters are a bit more difficult. At low levels they might pick up levels in other spellcasting classes to cast more low level spells. The sorcerer might pick up a level of wizard or beguiler while the cleric takes a level of archivist or favored soul. Furthermore, they will probably try to use early entry tricks to get into prcs at lower levels than intended.

In addition, Zombimode's remark about paragon classes (http://www.d20srd.org/srd/variant/races/racialParagonClasses.htm) is important since they are one of the few classes outside of normal base classes that can be entered at low levels.

The only other class that comes to mind is the Stoneblessed prc from Races of Stone.

[Tulya]

Cleric 1 / Sorcerer 1 / Any 1 / Mystic Theurge 1 / Geomancer (cleric) 1
With Versatile Spellcaster and Heighten Spell

Sorcerer 1 / Cleric 1 / Any 1 / Mystic Theurge 1 / Geomancer (sorcerer) 1 / Acolyte of the Skin 1
With Versatile Spellcaster, Heighten Spell, and Practiced Spellcaster (sorcerer)

At first blush, this is the best I've come up. Both builds end up with the capacity to cast equivalent to 3rd level spells. Thereafter, they can continually splash full spellcasting prestige classes so long as they balance their feat budget.

[Mnemnosyne]

There's several caster classes available early, if you use various early entries. The sorcerer can qualify for a number of prestige classes with Versatile Spellcaster and Heighten Spell, both useful metamagic feats and unambiguously acceptable.

By RAW, the cleric can qualify with Versatile Spellcaster, because he qualifies for the feat because of his spontaneous casting of cure/inflict spells, and the feat says nothing about having to be used on spontaneous spells only.

The real trick I suppose would be finding 19 different PrC's that all advance casting at 1st level AND have sufficiently easy qualifications that you can get into them all the way up. You're likely to eat up all the easy ones in the first few levels.

For the cleric, though, I have this suggestion:

Level 1: Cloistered Cleric 1
Feats: Extend Spell, Sanctum Spell, Spell Focus (Evil), Knowledge Devotion (Traded from Knowledge Domain).

Level 2: Binder 1

Level 3: Ardent 1
Feat: Improved Binding
Note: Gain Iron Will via Otyugh Hole if possible before this point. Otherwise, use feat this level to gain Iron Will.

Level 4: Incarnate 1

Level 5: Wizard (Conjurer) 1
ACF: Abrupt Jaunt, Martial Wizard.
Feat: Expeditious Dodge.

Level 6: Ur-Priest 1
Feat: Improved Counterspell

Level 7: Durthan 1

Level 8: Anima Priest 1
Note: Anima Mage divine adaptation as noted in the adaptation section for the class.

Level 9: Mystic Theurge 1
Feat: [Metamagic feat of choice].

Level 10: Seeker of the Misty Isle 1

Level 11: Contemplative 1
Domain: Law.

Level 12: Church Inquisitor 1
Feat: Shape Soulmeld (Something)

Level 13: Paragnostic Apostle 1
Note: 8th level spells become available; Dark Chaos Feat Shuffle possible. Shuffle elf weapon proficiencies into: Bonus Essentia, Endurance, Mobility, Combat Casting.

Level 14: Spelldancer 1.

Level 15: Sapphire Hierarch 1.
Feat: [Metamagic feat of choice, probably persistent spell].

I'm not sure that all the skills add up. The feats are legal, but I didn't check skill points. Ardent can actually be replaced with something else; warlock maybe to grab a useful low-level invocation; I was going to toss in a level of psychic theurge, but I decided it would be more effective to save the feat that I would have used on practiced manifester for a metamagic feat. We're using Sanctum Spell to cast 2nd level spells, thus qualifying for things like Mystic Theurge and Anima Priest. Alternately, the whole Incarnate/Sapphire Hierarch could be replaced, since that's eating two feats.

This build leaves the cleric with 5 more levels to work with, and he's got full casting as a cleric, a couple domains from Seeker of the Misty Isle and Contemplative, as well as infinite metamagic casting from Spelldancer. The last 5 levels could just as easily improve wizard casting, giving casting as a 7th level wizard. Or they could improve melee ability, since with full urpriest casting and persistomancy through Spelldancer, he's already got some really solid melee going on. Could add some maneuvers on top of that by grabbing levels of warblade, crusader, and swordsage, then tossing in two initiator PrC's.