Now then, on to the issue of "I hate math."
1) Concerning Thac0: it's counter-intuitive. I didn't bother with 2e, so I can't comment beyond that as to it's faults/merits.
2) At high levels, every additional character has the potential to increase the complexity of an individual, and spellcasters do so exponentially. I run an Epic level game with a druid, archmage and cleric. Spell power is considerable, and it's interaction can be intimidating. Add in the various abilities and magic items a group may have, and you've got a lot of numbers.
3) Playing with a group at a con is very different from an experienced group, as has been mentioned. Uncertain social interactions further muddy the waters.
4) Players should be expected to be responsible for helping with the math, and being responsible for their own calculations. Don't choose to play a super-archer unless you know how range increments work, the effects of firing into melee, and so on. Don't be a spellcaster and not know what your touch BAB is, or what the DCs of your spells are. Don't wait for your turn to decide your action. Read the spell description before your turn. Figure out your AC, and how any of your readied spells might modify them. And so on, and so on.
5) I use
DM Genie to track various effects in combat, and love it. You can just as easily create 3x5' cards (which we also do) for each spell in play. When you cast it, put it on the table for the other PCs to see, so they can refer to the cards on the table, and do quick tabulation on the fly, as needed.
6) Figure out what your totally debuffed AC is. Calculate all your bonuses, and be prepared for when you are flatfooted, or denied your dex bonus, and so on. If it's not a con, and you can't trust your players to help with the math, there may be other problems.