I don't think I've ever seen a great portable street map of Beijing (would not surprise me if one existed - though it might be in Chinese). Hopefully someone else here (Moondog, Peter etc) can help.

As for guidebooks, what's the purpose? If its to give you an itinerary and sightseeing/eating suggestions - then ignore them and use the search function on this site. If its for historical blurbs and other things like that, then you'd be best served avoiding Lonely Planet and maybe doing the Eyewitness Guide?

Best thing to do IMO, is to go to a bookstore and look for Beijing specific (not China) books and browse through them to see what fits your need best. There are a lot out there and more and more new ones. Another idea is getting on the ground and getting a copy of the Insider's Guide to Beijing -which should have some maps and a ton of listings/ideas (the first one I saw was the 2005 edition - updated every year and its probably 2x thicker now)