Because 4th edition D&D bases multi-classing on feats instead of mixing levels, I'll have to choose a primary class from which to rebuild my classic fighter/magic-user/thief (FMUT). Of the eight classes in the new Player's Handbook:
Cleric: The cleric has toe-to-toe combat potential, ritual casting, and prayers that could be slightly tweaked to pass for classic spells. However, there's little overlap with what I want for the thief, and its spellcasting doesn't feel "dangerous" enough.
Fighter: The fighter has some of the best weapon and armor options, of course, but I'll have to use feats to get just about all the spells and skills I want.
Paladin: The paladin is another divine class, but that divine power is geared towards melee buffing, allowing me to retain a more arcane flavor for the serious spellcasting. Again, the thief aspect is really lacking, but the availability of Charisma powers puts the paladin slightly ahead of the fighter in the running.
Ranger: The ranger has excellent combat and skill potential, especially if the FMUT is more of an archer than a duelist. It benefits more from Wisdom than Intelligence, though, making arcane spellcasting a bit of a stretch.
Rogue: The rogue is what they call the thief now, and it's more of a front-runner than the fighter or the wizard primarily because it offers both the requisite skills and the minimum combat options.
Warlock: Hmm, Charisma or Constitution based arcane spells, light armor and weapons, access to the Thievery skill... the warlock is a serious contender for the FMUT on all fronts. The warlock's curse even makes a nice substitute for the thief's backstabbing or the fighter's strength. It will need some shoring up, though.
Warlord: Slightly less buff than the fighter and paladin, but the warlord is still a decent combatant. Additionally, this class rewards investment in Charisma and/or Intelligence, one of which will be my primary spellcasting abilities. Still, it'll take a lot of feats to get those spells and skills.
Wizard: Like the fighter, the wizard fulfills only one of the FMUT's roles. No armor, no skills-- it's easier to pick up a few spells through feats than to pick up all the hit points and proficiencies I'll need.
Prioritizing the aspects of the FMUT would go a long way towards narrowing my options. For the sake of moving forward, let's say...
- I want the "thief" aspect for negotiating dungeons and choosing my foes.
- I want the "magic user" aspect for opening salvos and dealing with logistical problems.
- I want the "fighter" aspect for serious hand-to-hand encounters.
Put that way, my choice of primary class suddenly becomes a little clearer. Stealth and Thievery are the only parts of the thief I really need, and I'll be satisfied with ritual casting and a spell or two per encounter. Therefore, I need to choose a fighter-ish primary class. In this case, I'm going to have to go with the warlord-- it has excellent melee options, and gets plenty of mileage out of Intelligence. I can take the Arcane Initiate feat to get my first per-encounter spell and training in the Arcana skill (the first step towards ritual casting). All that's missing is the roguish aspect... but I can make that up with my choice of race for the character.
In keeping with the classic AD&D restrictions, I had originally intended to make my FMUT an elf or half-elf. As it turns out, the 4th edition eladrin fits the bill perfectly. The eladrin is elf-like enough to maintain the old aesthetic, gets a boost to Intelligence and Dexterity (two of the attributes I'll need), and has a nifty short range teleportation power that enhances the "MU" aspect. More importantly, the eladrin gets additional training in any one skill, so I can grab Thievery or Stealth. For the time being I'll take Thievery-- alert guards I can deal with, but locks and traps demand training.
Next, I'll start putting the pieces together for a 1st level draft.