When Capitol Hill Block Party's 2009 lineup was announced late April, what was already the hippest music festival in Seattle broke its own mold and became even more hip. Headliner Sonic Youth put a regal stamp on it - the American band's stayed ahead of the alternative rock curve for 28 years - but the buzz was bigger: No bad music. 50-something acts. Many experimental. All good.

Since then, a special kind of anticipation has been killing local music nerds, along with the usual anticipation of party people for one of Seattle's best parties.

Rejoice: the Block Party is here. Friday and Saturday, thousands of people and (mostly rock) artists will make a joyful noise heard from the downtown ferry docks to the Central District.

The festival's grown every year for more than a decade because it's fun. Show up with friends or alone, and whether or not you pay attention to what's on stage, if you're friendly, you'll meet people. If you drink, you'll not drink alone (but you will drink in a beer garden). If you holler, expect a holler back. Uncomfortable in large crowds? The Block Party's not for you. Feel like being social? The Block Party is your best friend.

It currently resides in Seattle's live music epicenter, Pike Street's 10th and 11th Avenue intersections, where clubs and coffee shops are rife with musicians and scene-makers. Nighttime there is a perpetual party, its sidewalks a constant catwalk for fashion peacocks and an equally interesting peanut gallery for people-watchers. During the Block Party, the whole area's not only on vacation, but steroids. It's a party by party-people's standards.

And this year, the music is exciting even by jaded hipsters' standards. Too bad to use the word "hipster," but it fits the Block Party: on the East Coast, you could enter a drawing at Urban Outfitters and win a flight to Seattle to witness the hipness.

I've learned not to try and see every artist at a festival, and that's hard with Block Party. There are too many good bands. Maldives and Moondoggies are great, but the local roots-rockers play around town all the time. Do I see them? Truckasauras is one of my favorites, period, but so is the Thermals, and they play at the same time. What should I do? Hell, the Vera stage on Friday is its own art-rock festival, with Audacity, Flexions, Bow + Arrow, Micachu and the Shapes, Past Lives, Starf****r, and Mika Miko playing consecutively from 4:00 to 10:00. All the rap is during the headliners. Clearly, eggs must be broken if an omelet is to be made. I suggest making a loose battle plan but staying open to whimsy and word-of-mouth upon arrival.

What I deem can't-miss acts, in order of unmissability:

Sonic Youth
Saturday at 10:30 on the main stage

The New York City band will most likely stick to songs from new album "The Eternal," which is back-to-basics Sonic Youth: mostly ice-cold grooves and noisy guitar techniques. Honed over a relentlessly creative 28-year career, the band's sound has graduated to "classic" rank in the American rock avant garde.

Deerhunter and Black Lips
Friday at 6:30 and 7:45 on the main stage

These Atlanta bands are two of the most exciting things in music today. Deerhunter's rock is sometimes billowing clouds of guitar color, and other times tuneful pop; "drone-y," "echo-y" and "grating" are all right around the corner, though. Black Lips is dirty, urban folk-rock, and sounds like the Rolling Stones or Velvet Underground with more ramshackle bravado and way better lyrics than both. The band is touched by a dangerous, perfect looseness.

Gossip
Saturday at 9:00 on the main stage

Front-woman Beth Ditto is the (screaming, soulful) voice of a new, gay generation, a superstar in the UK, and easily the most daring fashion icon in the world. Her Portland band makes minimalist, galvanizing dance-punk.

They Live!
Friday at 10:30 on the Neumo's stage

There's no local precedent for what this Capitol Hill rap group is doing. Every concert is a West Coast flag-waving, breakdancing, pro-weed, anti-meth, rap-as-theater extravaganza, with rappers Dro Boy and Bruce Illest vogue-ing in the eye of the choreographed storm.

Micachu and the Shapes
Friday at 7:00 on the Vera stage

The UK's bleeding, experimental edge is Micachu, and with the Shapes, her music's sure to be the weirdest at Block Party. Expect homemade instruments, maybe a vacuum cleaner, melodies that slant, squirm, and, against all odds, endear, and drums that bring together jazz, dance music, and the artiest tribal music one can imagine.

The Dutchess and the Duke
Friday at 4:30 on the main stage

There is no better band to start Block Party than Seattle duo Dutchess and the Duke, whose skeletal '60s-sounding acoustic rock is at once cool as a pair of Wayfarers and warm as sibling love. It's full of vocal harmonies and thorny, traditional guitar parts that speak to the unsentimental, wounded heart.