yeah, for any of the neogeo games, you can just use the 4 button on the bottom row, it works very well. As for straight rows or curved rows..there seems to be a big debate on this.
most of my panels have had the 2 straight rows layout, but on my newest panel, i decided to go with a curved layout....i see good and bad things about it.


i think the curved layout is more comfortable for most games. however the track n field type games seem a little weird with the curve, but it is not bad...the worst thing about a curved layout is when playing trackball games that use more than 1 button. I use the trackball with my right hand and buttons with the left...being that the buttons are curved for my right hand, it is a little awkward to use multiple buttons at once with my left hand (like in missile command). it is still playable, and affects very few games..but i just wanted to mention it.
most spinner games use very few buttons...most of them only use 1. same for the 4 way stick. since most spinner and 4 way games are single player, or alternating players, you can remap those games to use either player 1 or player 2 buttons, so that you dont have to install any additional buttons if you dont want.
also, do yourself a favor and install a trackball...you will definately want one. the ultimarc Utrak is awesome and easy to mount in a wood panel.
and if you want to cut down on the clutter, the ultimarc U360 sticks are very versatile....they work great as 8 way and 4 way sticks. i removed my dedicated 4 way stick when i built my new panel, because i bought u360s...i am very impressed with how they work. they work equally as well in street fighter as they do in donkey kong....they aren't cheap..but if you are trying to avoid a frankenpanel, they are a lifesaver