Indeed a common theme for a balanced party often means
2 tank types
1 cleric
1 arcane caster
1 rogue
1 utility or specialty class
I highly recommend leaving your main casters as single class as any levels in other classes will take away from their highest levels of spells.
Keep in mind the "normal" game with a full party will finish with characters between levels 15-17 if you complete most quests and that you can pretty accurately subtract any ECL penalties from those figures so plan accordingly. If you plan to go on and replay the same party through HOF then it may not be as critical but you will still want your characters to be "all they can be" in the normal game and do most of your "fooling around" later in HOF...at least thats my take.
I too recommend a sorcerer over a wizard as long as you are fairly familiar with D&D spells so you can make good choices. Wizards have some issues with higher level scrolls usually not being available as soon as thier higher level spell slots are which can be annoying.
Here's an idea for a very useful "second tank/back up cleric" character - try a barbarian X/Stormlord 4X either Ghostwise Halfling or Half-orc will work without exp penalty altho my first one was a halfling and he used hammers for both melee and ranged making use of the +1 bonus to thrown weapons. Theres a returning throwing hammer available for purchase early on (non retruning ones are too heavy to carry enough of) and a nicer one availble later. With a good build he will be able to tank up front - self buff - use the nice Stormlord offensive spells up front and late in the game the extra cleric spells will be quite useful over a plain warrior type thats only good at fighting...
Be aware that good and nuetral clerics can spontaneously cast healing spells while evil clerics spontaneosly cast harm which is much less useful. Also be aware that turn undead is only useful in some areas as opposed to constantly throughout the game.
For specialty classes I like druids as an offensive caster/archer/ summoner and shapeshifter for melee. This means I usually go with lower str (12) higher dex (14-16) high wis (max) builds since the shapeshifts will boost the str/con for melee (after level 5).
I like the bard too - with lingering song as first feat. They make great talkers/singers/archer/ back up arcane casters.
Some people go without rogues I like them especially MC'd with ranger - start rogue then a level or two of ranger then all rogue to 10 then all ranger is my choice. High dex archer finesse DW or high dex med str for more tanky build.
Have fun!