This is a Verizon map, not a Sprint map
My experience with the Thunderbolt that Verizon's coverage is pretty thorough for the metro area listed. The map says San Francisco, San Jose and Oakland have coverage. We've never found anyplace in the Bay area without good signal. Recently went to Boston, and had full coverage inside 495 and the north and south coasts.
Just because markets "have" 4G doesn't mean it's usably saturated. I'm in Phoenix and there was just a story on our local news from their "we fight fraud for your entertainment" departments about how this Sprint customer was upset over paying for 4G service that he wasn't able to actually take advantage of. They spoke to Sprint and various tech people and all said that 4G coverage is extremely spotty. Basically, the carriers are making sure to get at least a 4G tower or two wherever they can so they can claim they have coverage in all these cities, but you'll need to be within range of those very few towers to actually get it. So, realistically, it's as others have said before it's widespread - a year, 18 months, two years.
My experience with the Thunderbolt that Verizon's coverage is pretty thorough for the metro area listed. The map says San Francisco, San Jose and Oakland have coverage. We've never found anyplace in the Bay area without good signal. Recently went to Boston, and had full coverage inside 495 and the north and south coasts.