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If you use SMT, the side(s) you put the parts on can't really be a plane layer. However, the common thing is to put power and ground layers as the two inner layers, and then make the two outer layers to be signal layers. The problem with that is that anywhere you have a via for a trace to go from one signal layer (let's say in the X direction) to the other layer (let's say in the Y direction), the plane it was referenced against changes, so you would need to have bypass capacitor from one plane to the other at that point, as close to the via as possible, otherwise the return path is disrupted. On a small board with 74HC logic it won't matter; but as you get into bigger boards and faster edges, AC performance may suffer. We probably won't be seeing situations bad enough on this forum however that it would totally keep it from working. What you could do is make the top a signal layer, the next layer down the ground plane, then next the other signal layer, and make the back a power plane. You might get it routed on a smaller board (meaning the maximum signal trace length will be shorter) by having three signal layers and one ground plane and just routing power along with the signals, and of course putting an SMT bypass capacitor as close to each VDD pin as you can, with the via to ground at the side of the capacitor (to minimize inductance, as Dr. Howard Johnson shows in one of his articles) instead of off the end.
_________________ http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?
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