You would need two joysticks for Battlezone (with a top firing button), I would think ... and a spinner with minimum two buttons for other games as well. Add to that coin, player 1 and 2 start and couple other admin buttons.
The two joysticks will also be used for Black Widow and maybe QB-3. You will definately want 5 buttons in an "asteroids" layout so you can take advantage of Asteroids, Asteroids Deluxe, Gravitar, Ripoff, Star Castle, Armor Attack(1 player), Barrier, Space Duel, etc. You can use the spinner for Star Trek, Major Havoc, Tac Scan, Tempest, Cosmic Chasm, Boxing Bugs, Speed Freak, and maybe Lunar Lander. All of the other games I think use combinations of those basic controls.
There was a spreadsheet floating around at one time that had all of the vector games and controls on it.
ArcadeMaze
To this I would add: analog stick for Red Baron, Aztarac, and Topgunner (maybe SW and ESB, too, although yoke would be best). You also need a sixth button in the "Asteroids" layout for Solar Quest. This can quickly get out of hand if you don't have a huge CP. This is why I ultimately went for separate panels. Just too much crap to stuff into one panel.
One panel has two "Asteroids" setups with six buttons, one has analog stick, spinner, and four play buttons (Star Trek needs four and don't forget you need a spinner for Aztarac and Zektor), one with two button 8-ways (go with Groovy Game Gear, not Happs; worth the extra money) and TB (Warrior also needs 8-ways with buttons), and one with original BZ sticks. This is what I have so far. I also have parts for a yoke panel, a MH panel (I'm going to try to use a "one-way" trackball (?) from Kick), a Lunar Lander panel, and even a Speed Freak panel. Maybe I'm going overboard, but if I'm going to have a mame machine that only plays about 35 games, I want to play them right!
That said, you can play many of the games acceptably with two Asteroids button layouts, a spinner, two eight-ways with buttons, and a trackball. That's really not all that many controls. The good news is that you don't need to include the standard "eight-way with seven buttons just to the right" setup that all of the regular mame panels seem to include, or a four-way.
P.S. Arcademaze, do you have sound yet? I'm sorry I haven't gotten back with you, but we just moved and my PC was, and still is, packed away (somewhere). I'll get you those settings as soon as I can.