SF is hard to do on the cheap, but you can get much better hotel rates down by SFO or Oakland/Berkeley and take BART into town for the game. Then again, given the economy, there are probably a lot of really good deals right now, especially last-minute and in the middle of the week. There are a lot of hotels down by Union Square and Fisherman's Wharf and then along the Embarcadero, all of which you'll be able to jump on an N or T train to AT&T Park from (if you stay by the wharf, you'll need to transfer from the F at the Embarcadero stop). San Francisco is actually a really small town and you can walk most anywhere. Yeah, make sure you have tickets--it's a lot harder for this particular series given it's the opener, although you'll likely be able to snag a pair of something day of, especially now that Manny's in LA. There are a lot of touts walking up and down King and 3rd Street, selling, on most game days, and I wouldn't expect the opener to be too different. And yeah, bring a heavier coat--the park is right on the water, and San Francisco Bay will never be mistaken for the Caribbean. Any other specifics, just ask me...I know John Brew will also be here for the Thursday game this series; I'm not sure who else will be here for Opening Day.