I started playing some off-line games at Marathon speed, so I started using it as a way to get past the initial tedium of the first 100 or so turns of Marathon, where you have only one unit to move around (and he always spends several turns healing, of course) and when you do manage to finish building a Worker, there's very little for him to do.
Lately, though, I'm thinking of going back to regular starts and just dealing with the lack of activity in the initial few turns; I find that the AI doesn't handle advanced starts very well, whereas they can give a human a huge advantage. The AI seems to always spend its points on Settlers and cities, whereas I usually spend them on techs. So I have more of the map revealed initially and I know where the copper or horses are. The standard "blind start" is more of a challenge.