One thing that I've succeeded in doing in my time away from game development was to play a lot of games. I played my share of new AAA titles on my 360 but I also got back into classic arcade gaming in a big way. I now own an arcade cabinet with a few select PCBs from back in the day and even have a personal best of over 300k on Frogger. :)
In my return to the 80's I've really noticed how great a lot of the classic game play elements were. It's amazing how some fairly simple hand/eye twitch elements can be so addictive. Something about them makes you want to play the same game over and over again to hone your skills and add a little bit more to your score. Of course there are a lot of crappy games from the golden age but there's crap anywhere you look. My goal is to mine the gold from the crap and use the good elements as the inspiration for my new project.
Just to be clear inspired by the classics doesn't mean recreating the classics. I think a lot of the problems that "retro" games have had in the modern market it that most of the time they just end up being a straight port with new fancy graphics. This works for something like Monkey Island which was a great game because of the story, this doesn't necessarily work for a one dimensional 80's arcade game. The key is to simmer out the elements of a classic and add in modern twists without losing the original feel. Is this an easy thing to do? No, and I'm not sure if I can do it successfully but I think it'll be fun trying.