Hello,
I’m not a professional, I’ve done what I consider to be hobbyist-quality work with Eagle. I use Eagle because it’s the tool that I know how to use, not because I particularly like it. I do often use the autorouter, even though I know it’s frowned on by many. Over the years my projects have ranged from simple to moderately complex 2-layer boards, usually 100mm square or less. I’ve never considered a 4-layer board under the assumption that it would be cost prohibitive to do so. Checking one of the online quotation sites, it shot me a quote for a 4-layer board that’s only 11% more than a 2-layer board. That’s assuming I used the quotation tool correctly and didn’t mess something up… which is always possible.
Anyhow, I have a board with about a dozen ICs on it, and it seems like it sure would be convenient to have Vcc and GND on separate layers. It would make the signal layers cleaner not having to deal with the power traces, and it would lead to nice big power and ground planes for all the ICs. I was thinking of just dumping Vcc and GND polygons in the middle, then going about the signal traces like I normally would on the top and bottom. I don’t need or want to do anything fancy, no blind vias, no buried vias.
What I’m looking for is any tips for making the transition from 2-layer to 4-layer, any pitfalls to avoid, etc.  
Thanks,