I was trying the advice on using a monk, and for fun sk'd him to lvl 40 to see what the end result would be for a second. He's a thrashy machine. What is the best melee output class(es) with and without spellups? Monk was tossing 20+ damage sometimes with only 18 str.

Your monk through the course of the game will probably end up with a damage of about the mid 30's per hit without criticals for like 4 hits a round when you get up to about 21 strength. They are pretty well destructive.

I'm actually glad that I used the Oversight HLA's because with things like Critical Strike, Smite, and GWW the monk would have been just rediculous.

A Paladin with Holy Avenger or a fighter with the flail of ages or Staff of the Ram +6 can do some serious damage too though.

f/m whacking a malistoned enemy with silver sword while using GWW.

I am assuming that this does not include the thief class as I often see hits close to 400 (usually CF in on hand and that cool little dagger from the BoM items that increases you backstab multiplier by 3, so with an assassin, my favourite class, it is possible to get a multiplier of 10)
Other than that I have seen around 70 - 80 on a critical hit with CF in the on hand and Crom faeyr in the other with a fighter.