Combat help, I need to be more tactical

[Nail]

...But during the game he would continuously be looking in books coming up with ideas on combos for future powergaming tactics. So I'm not sure what to expect.

Don't worry about this too much. "Future powergaming tactics" = an interesting wish list that you are now privy to. Nothing more.

If there's anything to worry about, it's the type of player that sits at home for hours, pouring over the books, building the perfect spell list (or whatever) for your very next session. ...not that I ever did that.

...For all the melee fighter goons; I needed to roll natural 20's just to hit him.

Again, no biggie. That's what goons are supposed to do, right? Target practice for the heroes. Just watch any action movie.

One of the mook's ("goon's") primary purpose in 3.x D&D is battlefield control. They're not really there to do most of the damage. They are there to deny movement routes of the PCs, and open up avenues for the main bad guys. (Note the plural...it's no good just having one main bad guy.)

The other purpose of the mooks? To use up the resources (read: spells) of the PCs. Use two to three widely spaced (> 1 hour between) mook encounters, then hit them with the main encounter. By this time it's quite likely the "powergamer" has used up most of his good spells.

Along the same lines, try a two to three stage combat, in which the initial group is joined by groups of combatants after 3 rounds. The "Big Boom" spells of the PCs will be gone by the time the last wave of enemies enter the fray. I've nearly had TPKs this way, even when the players were top-notch gamers.